Condensed Consolidating Financial Statements Condensed Consolidating Statement Of Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Net income (loss)	$ 44,377	$ 42,302	$ 96,236	$ 85,610
Amortization of loss on cash flow hedge	215	215	646	646
Foreign currency translation adjustment, net	211	(1,167)	191	(164)
Actuarial loss	20	0	60	0
Other comprehensive income (loss), net of tax	446	(952)	897	472
Comprehensive income (loss)	44,823	41,350	97,133	86,082
Parent [Member]
Net income (loss)	44,377	42,302	96,236	85,610
Amortization of loss on cash flow hedge	215	215	646	646
Foreign currency translation adjustment, net	1	(15)	15	52
Actuarial loss	0		0
Actuarial pension loss, net of tax				0
Other comprehensive income (loss), net of tax	216	200	661	698
Comprehensive income (loss)	44,593	42,502	96,897	86,308
Guarantor Subsidiaries [Member]
Net income (loss)	(473)	530	6,200	8,494
Amortization of loss on cash flow hedge	0	0	0	0
Foreign currency translation adjustment, net	1	(93)	5	(76)
Actuarial loss	20		60
Actuarial pension loss, net of tax				(10)
Other comprehensive income (loss), net of tax	21	(93)	65	(86)
Comprehensive income (loss)	(452)	437	6,265	8,408
Non-Guarantor Subsidiaries [Member]
Net income (loss)	27,502	4,656	35,875	10,562
Amortization of loss on cash flow hedge	0	0	0	0
Foreign currency translation adjustment, net	207	(1,078)	181	17
Actuarial loss	0		0
Actuarial pension loss, net of tax				0
Other comprehensive income (loss), net of tax	207	(1,078)	181	17
Comprehensive income (loss)	27,709	3,578	36,056	10,579
Eliminations [Member]
Net income (loss)	(27,029)	(5,186)	(42,075)	(19,056)
Amortization of loss on cash flow hedge	0	0	0	0
Foreign currency translation adjustment, net	2	19	(10)	(157)
Actuarial loss	0		0
Actuarial pension loss, net of tax				0
Other comprehensive income (loss), net of tax	2	19	(10)	(157)
Comprehensive income (loss)	(27,027)	(5,167)	(42,085)	(19,213)
Consolidated [Member]
Net income (loss)	44,377	42,302	96,236	85,610
Amortization of loss on cash flow hedge	215	215	646	646
Foreign currency translation adjustment, net	211	(1,167)	191	(164)
Actuarial loss	20		60
Actuarial pension loss, net of tax				(10)
Other comprehensive income (loss), net of tax	446	(952)	897	472
Comprehensive income (loss)	$ 44,823	$ 41,350	$ 97,133	$ 86,082