Condensed Consolidating Statement Of Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Condensed Statement of Income Captions [Line Items]
Net income	$ 21,594	$ 23,110
Other comprehensive income (loss), net of tax:
Amortization of loss on cash flow hedge	215	215
Foreign currency translation adjustment	(1,447)	521
Other comprehensive income (loss), net of tax	(1,232)	736
Comprehensive income	20,362	23,846
Parent [Member]
Condensed Statement of Income Captions [Line Items]
Net income	21,594	23,110
Other comprehensive income (loss), net of tax:
Amortization of loss on cash flow hedge	215	215
Foreign currency translation adjustment	(1,447)	521
Other comprehensive income (loss), net of tax	(1,232)	736
Comprehensive income	20,362	23,846
Guarantor Subsidiaries [Member]
Condensed Statement of Income Captions [Line Items]
Net income	2,338	3,603
Other comprehensive income (loss), net of tax:
Amortization of loss on cash flow hedge	0	0
Foreign currency translation adjustment	0	0
Other comprehensive income (loss), net of tax	0	0
Comprehensive income	2,338	3,603
Non-Guarantor Subsidiaries [Member]
Condensed Statement of Income Captions [Line Items]
Net income	8,856	7,262
Other comprehensive income (loss), net of tax:
Amortization of loss on cash flow hedge	0	0
Foreign currency translation adjustment	(1,447)	521
Other comprehensive income (loss), net of tax	(1,447)	521
Comprehensive income	7,409	7,783
Eliminations [Member]
Condensed Statement of Income Captions [Line Items]
Net income	(11,194)	(10,865)
Other comprehensive income (loss), net of tax:
Amortization of loss on cash flow hedge	0	0
Foreign currency translation adjustment	1,447	(521)
Other comprehensive income (loss), net of tax	1,447	(521)
Comprehensive income	(9,747)	(11,386)
Consolidated [Member]
Condensed Statement of Income Captions [Line Items]
Net income	21,594	23,110
Other comprehensive income (loss), net of tax:
Amortization of loss on cash flow hedge	215	215
Foreign currency translation adjustment	(1,447)	521
Other comprehensive income (loss), net of tax	(1,232)	736
Comprehensive income	$ 20,362	$ 23,846