Condensed Consolidating Statement Of Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2016	Mar. 31, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Condensed Statement of Income Captions [Line Items]
Net income	$ 47,565	$ 21,163	$ 41,419	$ 107,550	$ 98,826
Other comprehensive income, net of tax:
Amortization of loss on cash flow hedge	215		215	646	646
Foreign currency translation adjustment	137		(951)	1,036	(2,223)
Other comprehensive income (loss), net of tax	352		(736)	1,682	(1,577)
Comprehensive income	47,917		40,683	109,232	97,249
Parent
Condensed Statement of Income Captions [Line Items]
Net income	47,565		41,419	107,550	98,826
Other comprehensive income, net of tax:
Amortization of loss on cash flow hedge	215		215	646	646
Foreign currency translation adjustment	137		(951)	1,036	(2,223)
Other comprehensive income (loss), net of tax	352		(736)	1,682	(1,577)
Comprehensive income	47,917		40,683	109,232	97,249
Guarantor Subsidiaries
Condensed Statement of Income Captions [Line Items]
Net income	3,356		2,801	12,408	9,263
Other comprehensive income, net of tax:
Amortization of loss on cash flow hedge	0		0	0	0
Foreign currency translation adjustment	0		0	0	0
Other comprehensive income (loss), net of tax	0		0	0	0
Comprehensive income	3,356		2,801	12,408	9,263
Non-Guarantor Subsidiaries
Condensed Statement of Income Captions [Line Items]
Net income	10,358		6,465	23,236	21,490
Other comprehensive income, net of tax:
Amortization of loss on cash flow hedge	0		0	0	0
Foreign currency translation adjustment	137		(951)	1,036	(2,223)
Other comprehensive income (loss), net of tax	137		(951)	1,036	(2,223)
Comprehensive income	10,495		5,514	24,272	19,267
Eliminations
Condensed Statement of Income Captions [Line Items]
Net income	(13,714)		(9,266)	(35,644)	(30,753)
Other comprehensive income, net of tax:
Amortization of loss on cash flow hedge	0		0	0	0
Foreign currency translation adjustment	(137)		951	(1,036)	2,223
Other comprehensive income (loss), net of tax	(137)		951	(1,036)	2,223
Comprehensive income	$ (13,851)		$ (8,315)	$ (36,680)	$ (28,530)