Condensed Consolidating Statements of Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Condensed Financial Statements, Captions [Line Items]
Net income	$ 80,469	$ 91,515	$ 104,882	$ 104,653	$ 77,864	$ 73,445	$ 75,722	$ 84,592	$ 381,519	$ 311,623	$ 261,225
Other comprehensive income, net of tax:
Foreign currency translation									(51,979)	14,056	12,921
Net change in unrecognized gains/losses on derivative instruments, net of tax									2,195	4,495	(3,201)
Unrealized gain on pension plan, net of tax									(10,452)	701	0
Total other comprehensive (loss) income									(60,236)	19,252	9,720
Total comprehensive income									321,283	330,875	270,945
Parent Company
Condensed Financial Statements, Captions [Line Items]
Net income									381,519	311,623	261,225
Other comprehensive income, net of tax:
Foreign currency translation									(51,979)	14,056	12,921
Net change in unrecognized gains/losses on derivative instruments, net of tax									2,195	4,495	(3,201)
Unrealized gain on pension plan, net of tax									(10,452)	701
Total other comprehensive (loss) income									(60,236)	19,252	9,720
Total comprehensive income									321,283	330,875	270,945
Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net income									335,489	271,491	234,399
Other comprehensive income, net of tax:
Foreign currency translation									(17,710)	7,168	5,278
Net change in unrecognized gains/losses on derivative instruments, net of tax									0	0	0
Unrealized gain on pension plan, net of tax									0	0
Total other comprehensive (loss) income									(17,710)	7,168	5,278
Total comprehensive income									317,779	278,659	239,677
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net income									92,962	82,047	44,152
Other comprehensive income, net of tax:
Foreign currency translation									(49,559)	15,495	12,334
Net change in unrecognized gains/losses on derivative instruments, net of tax									(444)	1,322	(519)
Unrealized gain on pension plan, net of tax									(10,452)	701
Total other comprehensive (loss) income									(60,455)	17,518	11,815
Total comprehensive income									32,507	99,565	55,967
Consolidation, Eliminations
Condensed Financial Statements, Captions [Line Items]
Net income									(428,451)	(353,538)	(278,551)
Other comprehensive income, net of tax:
Foreign currency translation									67,269	(22,663)	(17,612)
Net change in unrecognized gains/losses on derivative instruments, net of tax									444	(1,322)	519
Unrealized gain on pension plan, net of tax									10,452	(701)
Total other comprehensive (loss) income									78,165	(24,686)	(17,093)
Total comprehensive income									$ (350,286)	$ (378,224)	$ (295,644)