SCHEDULE 13G

Amendment No. 0 
Mediacom Communications Corporation 
Common Stock 
Cusip #58446K105 


Cusip #58446K105 
Item 1:	Reporting Person - FMR Corp.
Item 4:	Commonwealth of Massachusetts
Item 5:	39,500 
Item 6:	0 
Item 7:	6,283,585 
Item 8:	0 
Item 9:	6,283,585 
Item 11:	10.320% 
Item 12:	    HC


Cusip #58446K105  
Item 1:	Reporting Person - Edward C. Johnson 3d 
Item 4:	United States of America
Item 5:	0 
Item 6:	0 
Item 7:	6,283,585 
Item 8:	0 
Item 9:	6,283,585 
Item 11:	10.320% 
Item 12:	IN 


Cusip #58446K105 
Item 1:	Reporting Person - Abigail P. Johnson 
Item 4:	United States of America
Item 5:	None 
Item 6:	None 
Item 7:	6,283,585 
Item 8:	None 
Item 9:	6,283,585 
Item 11:	10.320% 
Item 12:	    IN



SCHEDULE 13G - TO BE INCLUDED IN STATEMENTS
FILED PURSUANT TO RULE 13d-1(b) or 13d-2(b)


Item 1(a).	Name of Issuer:	

		Mediacom Communications 
Corporation 

Item 1(b).	Name of Issuer's Principal Executive Offices:

		100 Crystal Run Road,  
		Middletown, New York  10941  

Item 2(a).	Name of Person Filing: 

		FMR Corp.

Item 2(b).	Address or Principal Business Office or, if None, 
Residence:

		82 Devonshire Street, Boston, 
Massachusetts  02109

Item 2(c).	Citizenship:

		Not applicable

Item 2(d).	Title of Class of Securities:

		Common Stock 

Item 2(e).	CUSIP Number:  

		58446K105 

Item 3.	This statement is filed pursuant to Rule 13d-1(b) or 13d-2(b) 
and the person filing, FMR Corp., is a parent holding company 
in accordance with Section 240.13d-1(b)(ii)(G).  (Note:  See 
Item 7).

Item 4.	Ownership

	(a)	Amount Beneficially Owned:	6,283,585 

	(b)	Percent of Class:	10.320% 

	(c)	Number of shares as to which such 
person has:  

	(i)	sole power to vote or to direct 
the vote:	39,500 

	(ii)	shared power to vote or to 
direct the vote:	0 

	(iii)	sole power to dispose or to 
direct the disposition of:	6,283,585 

	(iv)	shared power to dispose or to 
direct the disposition of:	0 



Item 5.	Ownership of Five Percent or Less of a Class.

	Not applicable.

Item 6.	Ownership of More than Five Percent on Behalf of Another 
Person.

	Various persons have the right to receive or the power to 
direct the receipt of dividends from, or the proceeds from the 
sale of, the Common Stock of Mediacom Communications 
Corporation.  No one person's interest in the Common Stock 
of Mediacom Communications Corporation is more than five 
percent of the total outstanding Common Stock.

Item 7.	Identification and Classification of the Subsidiary Which 
Acquired the Security Being Reported on By the Parent 
Holding Company.

	See attached Exhibit(s) A, B. 

Item 8.	Identification and Classification of Members of 
the Group.

	Not Applicable. See attached Exhibit A. 

Item 9.	Notice of Dissolution of Group.

	Not applicable.

Item 10.	Certification.

	By signing below I certify that, to the best of my knowledge 
and belief, the securities referred to above were acquired in the 
ordinary course of business and were not acquired for the 
purpose of and do not have the effect of changing or 
influencing the control of the issuer of such securities and 
were not acquired in connection with or as a participant in any 
transaction having such purpose or effect.

Signature

	After reasonable inquiry and to the best of my knowledge and 
belief, I certify that the information set forth in this Schedule 
13G in connection with FMR Corp.'s beneficial ownership of 
the Common Stock of Mediacom Communications 
Corporation at July 31, 2001 is true, complete and correct. 

August 10, 2001 			
Date

/s/Eric D. Roiter				
Signature

Eric D. Roiter				
Duly authorized under Power of Attorney
dated December 30, 1997 by and on behalf
of FMR Corp. and its direct and indirect
subsidiaries


SCHEDULE 13G - TO BE INCLUDED IN STATEMENTS
FILED PURSUANT TO RULE 13d-1(b) or 13d-2(b)

	Pursuant to the instructions in Item 7 of Schedule 
13G, Fidelity Management & Research Company 
("Fidelity"), 82 Devonshire Street, Boston, Massachusetts 
02109, a wholly-owned subsidiary of FMR Corp. and an 
investment adviser registered under Section 203 of the 
Investment Advisers Act of 1940, is the beneficial owner of 
6,245,785 shares or 10.258% of the Common Stock 
outstanding of Mediacom Communications Corporation  
("the Company") as a result of acting as investment adviser 
to various investment companies registered under Section 8 
of the Investment Company Act of 1940.  The number of 
shares of Common Stock of Mediacom Communications 
Corporation owned by the investment companies at July 31, 
2001 included 267,085 shares of Common Stock resulting 
from the assumed conversion of $5,000,000 principal amount 
of MEDIACOM COMM 5.25% CSD 7/1/06 (53.417 shares 
of Common Stock for each $1,000 principal amount of 
debenture).

	Edward C. Johnson 3d, FMR Corp., through its 
control of Fidelity, and the funds each has sole power to 
dispose of the 6,245,785 shares owned by the Funds.

	Neither FMR Corp. nor Edward C. Johnson 3d, 
Chairman of FMR Corp., has the sole power to vote or direct 
the voting of the shares owned directly by the Fidelity Funds, 
which power resides with the Funds' Boards of Trustees.  
Fidelity carries out the voting of the shares under written 
guidelines established by the Funds' Boards of Trustees.

	Fidelity Management Trust Company, 82 Devonshire 
Street, Boston, Massachusetts 02109, a wholly-owned 
subsidiary of FMR Corp. and a bank as defined in Section 
3(a)(6) of the Securities Exchange Act of 1934, is the 
beneficial owner of  37,800 shares or 0.062% of the Common 
Stock outstanding of the Company as a result of its serving as 
investment manager of the institutional account(s). 

	Edward C. Johnson 3d and FMR Corp., through its 
control of Fidelity Management Trust Company, each has 
sole dispositive power over 37,800 shares and sole power to 
vote or to direct the voting of 37,800 shares of Common 
Stock owned by the institutional account(s) as reported 
above.

	Members of the Edward C. Johnson 3d family are the 
predominant owners of Class B shares of common stock of 
FMR Corp., representing approximately 49% of the voting 
power of FMR Corp.  Mr. Johnson 3d owns 12.0% and 
Abigail Johnson owns 24.5% of the aggregate outstanding 
voting stock of FMR Corp.  Mr. Johnson 3d is Chairman of 
FMR Corp. and Abigail P. Johnson is a Director of FMR 
Corp.  The Johnson family group and all other Class B 
shareholders have entered into a shareholders' voting 
agreement under which all Class B shares will be voted in 
accordance with the majority vote of Class B shares.  
Accordingly, through their ownership of voting common 
stock and the execution of the shareholders' voting 
agreement, members of the Johnson family may be deemed, 
under the Investment Company Act of 1940, to form a 
controlling group with respect to FMR Corp.

 


SCHEDULE 13G - TO BE INCLUDED IN STATEMENTS
FILED PURSUANT TO RULE 13d-1(b) or 13d-2(b)
RULE 13d-1(f)(1)  AGREEMENT

	The undersigned persons, on August 10, 2001, agree 
and consent to the joint filing on their behalf of this Schedule 
13G in connection with their beneficial ownership of the 
Common Stock of Mediacom Communications Corporation at 
July 31, 2001.

FMR Corp.

By   /s/Eric D. Roiter   			
	Eric D. Roiter
	Duly authorized under Power of Attorney
	dated December 30, 1997, by and on behalf
	of FMR Corp. and its direct and indirect 
	subsidiaries

	Edward C. Johnson 3d

By   /s/Eric D. Roiter   			
	Eric D. Roiter
	Duly authorized under Power of Attorney
	dated December 30, 1997, by and on behalf
	of Edward C. Johnson 3d

	Abigail P. Johnson

By   /s/Eric D. Roiter   			
	Eric D. Roiter
	Duly authorized under Power of Attorney
	dated December 30, 1997, by and on behalf
	of Abigail P. Johnson

	Fidelity Management & Research Company

By   /s/Eric D. Roiter   			
	Eric D. Roiter
	Senior V.P. and General Counsel