Debt (Narrative) (Detail) (USD $)	1 Months Ended	6 Months Ended			1 Months Ended	6 Months Ended		1 Months Ended	6 Months Ended		3 Months Ended	1 Months Ended				1 Months Ended	6 Months Ended		1 Months Ended		6 Months Ended	1 Months Ended		6 Months Ended	1 Months Ended		1 Months Ended	6 Months Ended	1 Months Ended	6 Months Ended	1 Months Ended	6 Months Ended			6 Months Ended								6 Months Ended	1 Months Ended	3 Months Ended	6 Months Ended	1 Months Ended	6 Months Ended	1 Months Ended	6 Months Ended
	May 09, 2012	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011	May 09, 2012 Maximum [Member]	Jun. 30, 2012 Maximum [Member] BasisPoint	Apr. 02, 2012 Maximum [Member]	May 09, 2012 Minimum [Member]	Jun. 30, 2012 Minimum [Member] BasisPoint	Apr. 02, 2012 Minimum [Member]	Mar. 31, 2012 Class A Common Stock [Member] Day	Nov. 07, 2008 1.875% Convertible Senior Notes due 2013 [Member]	May 16, 2008 1.875% Convertible Senior Notes due 2013 [Member]	Jun. 30, 2012 1.875% Convertible Senior Notes due 2013 [Member]	Dec. 31, 2011 1.875% Convertible Senior Notes due 2013 [Member]	Apr. 24, 2009 4.0% Convertible Senior Notes due 2014 [Member]	Jun. 30, 2012 4.0% Convertible Senior Notes due 2014 [Member]	Dec. 31, 2011 4.0% Convertible Senior Notes due 2014 [Member]	Apr. 13, 2012 8.0% Senior Notes due 2016 [Member]	Jul. 24, 2009 8.0% Senior Notes due 2016 [Member]	Jun. 30, 2012 8.0% Senior Notes due 2016 [Member]	Apr. 13, 2012 8.25% Senior Notes due 2019 [Member]	Jul. 24, 2009 8.25% Senior Notes due 2019 [Member]	Jun. 30, 2012 8.25% Senior Notes due 2019 [Member]	Apr. 13, 2012 Senior Notes [Member]	Jul. 24, 2009 Senior Notes [Member]	Apr. 02, 2012 Mobilitie Bridge Loan [Member]	Jun. 30, 2012 Mobilitie Bridge Loan [Member]	Apr. 02, 2012 Mobilitie Bridge Loan [Member] Maximum [Member]	Jun. 30, 2012 Mobilitie Bridge Loan [Member] Maximum [Member]	Apr. 02, 2012 Mobilitie Bridge Loan [Member] Minimum [Member]	Jun. 30, 2012 Mobilitie Bridge Loan [Member] Minimum [Member]	Jun. 30, 2012 Mobilitie Bridge Loan [Member] Currently [Member]	Jul. 13, 2012 Mobilitie Bridge Loan [Member] Subsequent Event [Member]	Jun. 30, 2012 2012 Term Loan [Member]	Jun. 30, 2012 2012 Term Loan [Member] Maximum [Member]	Jun. 30, 2012 2012 Term Loan [Member] Minimum [Member]	Jun. 30, 2012 2012 Term Loan [Member] Installment One [Member]	Jun. 30, 2012 2012 Term Loan [Member] Installment Two [Member]	Jun. 30, 2012 2012 Term Loan [Member] Thereafter [Member]	Jun. 30, 2012 2011 Term Loan [Member]	Dec. 31, 2011 2011 Term Loan [Member]	Jun. 30, 2012 Senior Notes Due 2020 [Member]	Jul. 13, 2012 Senior Notes Due 2020 [Member] Subsequent Event [Member]	Jun. 30, 2012 Revolving Credit Facility [Member]	Jun. 30, 2012 Revolving Credit Facility [Member]	Apr. 16, 2010 2010-1 Tower Securities [Member]	Jun. 30, 2012 2010-1 Tower Securities [Member]	Apr. 16, 2010 2010-2 Tower Securities [Member]	Jun. 30, 2012 2010-2 Tower Securities [Member]	Jun. 30, 2012 Tower Securities [Member]
Line of Credit Facility [Line Items]
Line of credit facility, principal amount																																			$ 200,000,000						$ 500,000,000				$ 700,000,000	$ 700,000,000
Eurodollar Rate margin, basis points						237.5			187.5																																0.0275
Base Rate margin, basis points						137.5			87.5																																0.0175
Line of credit facility, per annum commitment fee						0.50%			0.375%
Revolving Credit Facility accrued interest																																			2.75%						3.75%		5.75%			2.25%
Revolving credit facility under senior credit agreement							600,000,000			500,000,000
Additional borrowings under line of credit facility					700,000,000			600,000,000																																					200,000,000
Debt instrument, maturity date	May 09, 2017															Oct. 01, 2014				Aug. 15, 2016			Aug. 15, 2019				Apr. 01, 2013																	Jul. 15, 2020
Deferred financing fees	1,100,000																																		2,700,000
Borrowings under the Revolving Credit Facility		484,000,000	250,000,000																																										284,000,000	484,000,000
Repaid under the Revolving Credit Facility																																													200,000,000	200,000,000
Line of credit facility, remaining borrowing capacity		416,000,000
Aggregate principal amount of senior notes issued																																											800,000,000
Line of credit facility, outstanding																																											284,000,000
Base Rate floor																																									2.00%
Eurodollar Rate floor																																									1.00%
Repayments of long-term debt, quarterly																																									1,250,000
Percentage of par value price for issuance of term loan																																									99.75%
Repayments of debt		2,500,000																																							2,500,000
Debt instrument, principal balance														535,000,000	535,000,000		500,000,000	500,000,000																							495,000,000	497,500,000
Base Rate plus margin																													2.50%		2.00%					1.50%	1.00%
Eurodollar Rate plus margin																												3.50%	3.50%		3.00%		3.75%			2.50%	2.00%
Term loan principal repayment																																						2,500,000	3,750,000	5,000,000
Principal balance under bridge loan																												400,000,000							200,000,000
Aggregate principal amount under senior secured loan																											400,000,000
Deferred financing fees																									4,300,000		5,000,000
Consolidated Total Debt to Consolidated Adjusted EBITDA																														0.070		0.010
Equity component related to repurchases, convertible, effective interest rate													1.875%	1.875%			4.00%			8.00%	8.00%		8.25%	8.25%										5.75%										5.75%
Debt instrument principal payment																																		400,000,000
Proceeds from issuance of 2010 Tower Securities, net of fees paid		395,000,000																																													680,000,000		550,000,000
Securities, annual interest rate																																																4.254%		5.101%
Weighted average annual fixed coupon interest rate																																																			4.70%
Tower Revenue Securities anticipated repayment date																																																2015-04-16		2017-04-16
Tower Revenue Securities final maturity date																					2016			2019																								2040-04-16		2042-04-16
Debt instrument, issuance date													May 16, 2008
Convertible senior notes issued													550,000,000			500,000,000
Interest payable dates													May 1 and November 1			April 1 and October 1				February 15 and August 15			February 15 and August 15
Conversion rate, in shares													24.1196			32.9164
Common stock principal amount													1,000			1,000
Per share conversion price													$ 41.46			$ 30.38
Conversion premium													20.00%			22.50%
Last reported selling price													$ 34.55			$ 24.80
Initial strike price of warrants													$ 41.46				$ 30.38
Upper strike price of warrants													$ 67.37				$ 44.64
Terminated convertible note hedge transaction												55.00%
Common stock shares issuable		109,675,000		109,675,000								13,265,780
Common stock market price												$ 41.46
convertible senior notes effective interest rate, maximum														9.40%			13.00%
Carrying amount of the equity component														156,600,000			169,000,000
Convertible notes conversion criteria associated with common stock trading price		Last reported sale price of the Company's Class A common stock for at least 20 trading days in the 30 consecutive trading day period ending on the last trading day of the preceding calendar quarter is more than 130% of the applicable conversion price per share of Class A common stock on the last day of such preceding calendar quarter,
Applicable conversion price percentage		130.00%
Convertible notes conversion criteria associated with common stock and convertible notes trading price		Trading price per $1,000 principal amount of the Notes for each day in the measurement period was less than 95% of the product of the last reported sale price of Class A common stock
Common stock closing price per share											$ 39.49
Trading days											20
Consecutive trading day											30
Unsecured senior notes																				375,000,000			375,000,000			750,000,000
percentage of face value price for issuance of senior notes																				99.33%			99.152%																					100.00%
Debt instrument, aggregate principal amount redeemed																			131,300,000			131,300,000
Premium on redemption																									21,300,000
Debt discount																									$ 1,500,000