Intangible Assets, Net - Gross and Net Carrying Amounts for Each Major Class of Intangible Assets (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	$ 3,859,759	$ 3,846,534
Accumulated amortization	(774,300)	(712,401)
Net book value	3,085,459	3,134,133
Current contract intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	2,754,449	2,744,968
Accumulated amortization	(506,060)	(462,016)
Net book value	2,248,389	2,282,952
Network location intangibles [Member]
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	1,105,310	1,101,566
Accumulated amortization	(268,240)	(250,385)
Net book value	$ 837,070	$ 851,181