Debt - Carrying Values of Debt (Detail) (USD $) In Thousands, unless otherwise specified			9 Months Ended		9 Months Ended		9 Months Ended		9 Months Ended					9 Months Ended		9 Months Ended		1 Months Ended	9 Months Ended		1 Months Ended	9 Months Ended		9 Months Ended		9 Months Ended		9 Months Ended		9 Months Ended
	Sep. 30, 2013	Dec. 31, 2012	Sep. 30, 2013 4.254% Secured Tower Revenue Securities Series 2010-1 [Member]	Dec. 31, 2012 4.254% Secured Tower Revenue Securities Series 2010-1 [Member]	Sep. 30, 2013 5.101% Secured Tower Revenue Securities Series 2010-2 [Member]	Dec. 31, 2012 5.101% Secured Tower Revenue Securities Series 2010-2 [Member]	Sep. 30, 2013 2.933% Secured Tower Revenue Securities Series 2012-1 [Member]	Dec. 31, 2012 2.933% Secured Tower Revenue Securities Series 2012-1 [Member]	Sep. 30, 2013 2.240% Secured Tower Revenue Securities Series 2013-1C [Member]	Sep. 30, 2013 3.722% Secured Tower Revenue Securities Series 2013-2C [Member]	Sep. 30, 2013 3.598% Secured Tower Revenue Securities Series 2013-1D [Member]	Sep. 30, 2013 8.25% Senior Notes [Member]	Dec. 31, 2012 8.25% Senior Notes [Member]	Sep. 30, 2013 5.625% Senior Notes [Member]	Dec. 31, 2012 5.625% Senior Notes [Member]	Sep. 30, 2013 5.75% Senior Notes [Member]	Dec. 31, 2012 5.75% Senior Notes [Member]	May 16, 2008 1.875% Convertible Senior Notes due 2013 [Member]	Sep. 30, 2013 1.875% Convertible Senior Notes due 2013 [Member]	Dec. 31, 2012 1.875% Convertible Senior Notes due 2013 [Member]	Apr. 24, 2009 4.0% Convertible Senior Notes due 2014 [Member]	Sep. 30, 2013 4.0% Convertible Senior Notes due 2014 [Member]	Dec. 31, 2012 4.0% Convertible Senior Notes due 2014 [Member]	Sep. 30, 2013 Revolving Credit Facility [Member]	Dec. 31, 2012 Revolving Credit Facility [Member]	Sep. 30, 2013 2011 Term Loan B [Member]	Dec. 31, 2012 2011 Term Loan B [Member]	Sep. 30, 2013 2012-1 Term Loan A [Member]	Dec. 31, 2012 2012-1 Term Loan A [Member]	Sep. 30, 2013 2012-2 Term Loan B [Member]	Dec. 31, 2012 2012-2 Term Loan B [Member]
Debt Instrument [Line Items]
Debt instrument, Principal balance	$ 5,691,697	$ 5,440,073	$ 680,000	$ 680,000	$ 550,000	$ 550,000	$ 610,000	$ 610,000	$ 425,000	$ 575,000	$ 330,000	$ 243,750	$ 243,750	$ 500,000	$ 500,000	$ 800,000	$ 800,000			$ 468,836		$ 499,947	$ 499,987		$ 100,000	$ 180,529	$ 492,500	$ 187,500	$ 195,000	$ 109,971	$ 300,000
Debt, Carrying Value	5,648,328	5,356,103	680,000	680,000	550,000	550,000	610,000	610,000	425,000	575,000	330,000	242,340	242,205	500,000	500,000	800,000	800,000			457,351		458,535	430,751		100,000	180,218	491,518	187,500	195,000	109,735	299,278
Less: current maturities of long-term debt	(11,250)	(475,351)
Total long-term debt, net of current maturities	$ 5,637,078	$ 4,880,752
Debt instrument, maturity date			Apr. 15, 2015		Apr. 17, 2017		Dec. 15, 2017		Apr. 17, 2018	Apr. 17, 2023	Apr. 17, 2018	Aug. 15, 2019		Oct. 01, 2019		Jul. 15, 2020		May 01, 2013	May 01, 2013		Oct. 01, 2014	Oct. 01, 2014		May 09, 2017		Jun. 30, 2018		May 09, 2017		Sep. 28, 2019