Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2014

Fair Value Measurements [Abstract]

Summary Of Accrued Earnout Activity

	2014		2013
	(in thousands)
Beginning balance, December 31, 2013 and 2012 , respectively	$	30,063	$	9,840
Additions		11,048		31,704
Payments		(18,724)		(9,324)
Change in estimate		(7,310)		(1,585)
Foreign currency translation adjustments		9		(572)
Ending balance, December 31,	$	15,086	$	30,063

Summary Of Fair Values, Principal Balances, And Carrying Values Of Company's Debt Instruments

	As of December 31, 2014						As of December 31, 2013
	Fair Value		Principal Balance		Carrying Value		Fair Value		Principal Balance		Carrying Value
	(in thousands)
4.000% Convertible Senior Notes due 2014	$	—	$	—	$	—	$	1,479,859	$	499,944	$	468,394
8.250% Senior Notes due 2019		—		—		—		262,031		243,750		242,387
5.625% Senior Notes due 2019		511,250		500,000		500,000		514,375		500,000		500,000
5.750% Senior Notes due 2020		816,000		800,000		800,000		832,000		800,000		800,000
4.875% Senior Notes due 2022		721,875		750,000		744,150		—		—		—
4.254% 2010-1 Tower Securities		—		—		—		689,717		680,000		680,000
5.101% 2010-2 Tower Securities		576,901		550,000		550,000		586,586		550,000		550,000
2.933% 2012 Tower Securities		620,175		610,000		610,000		604,736		610,000		610,000
2.240% 2013-1C Tower Securities		420,776		425,000		425,000		408,442		425,000		425,000
3.722% 2013-2C Tower Securities		584,344		575,000		575,000		530,098		575,000		575,000
3.598% 2013-1D Tower Securities		330,551		330,000		330,000		318,856		330,000		330,000
2.898% 2014-1C Tower Securities		920,515		920,000		920,000		—		—		—
3.869% 2014-2C Tower Securities		629,474		620,000		620,000		—		—		—
Revolving Credit Facility		125,000		125,000		125,000		215,000		215,000		215,000
2011 Term Loan		—		—		—		180,980		180,529		180,234
2012-1 Term Loan		171,422		172,500		172,500		184,538		185,000		185,000
2012-2 Term Loan		—		—		—		110,383		109,971		109,745
2014 Term Loan		1,458,919		1,492,500		1,489,149		—		—		—
BNDES Loans		—		—		—		5,847		5,847		5,847
Totals	$	7,887,202	$	7,870,000	$	7,860,799	$	6,923,448	$	5,910,041	$	5,876,607