Condensed Consolidating Financial Statements Condensed Consolidating Statement Of Comprehensive Income (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Net income (loss)	$ 38,716,000	$ 42,744,000	$ 90,266,000	$ 100,909,000
Amortization of loss on cash flow hedge	215,000	215,000	646,000	646,000
Foreign currency translation adjustment	524,000	211,000	(1,803,000)	191,000
Actuarial loss	0	20,000	0	60,000
Other comprehensive income (loss), net of tax	739,000	446,000	(1,157,000)	897,000
Comprehensive income	39,455,000	43,190,000	89,109,000	101,806,000
Parent [Member]
Net income (loss)	38,716,000	42,744,000	90,266,000	100,909,000
Amortization of loss on cash flow hedge	215,000	215,000	646,000	646,000
Foreign currency translation adjustment	524,000	211,000	(1,803,000)	191,000
Actuarial loss		20,000		60,000
Other comprehensive income (loss), net of tax	739,000	446,000	(1,157,000)	897,000
Comprehensive income	39,455,000	43,190,000	89,109,000	101,806,000
Guarantor Subsidiaries [Member]
Net income (loss)	3,172,000	(477,000)	9,236,000	6,204,000
Amortization of loss on cash flow hedge	0	0	0	0
Foreign currency translation adjustment	0	1,000	0	5,000
Actuarial loss		20,000		60,000
Other comprehensive income (loss), net of tax	0	21,000	0	65,000
Comprehensive income	3,172,000	(456,000)	9,236,000	6,269,000
Non-Guarantor Subsidiaries [Member]
Net income (loss)	9,859,000	27,708,000	25,455,000	35,983,000
Amortization of loss on cash flow hedge	0	0	0	0
Foreign currency translation adjustment	524,000	209,000	(1,803,000)	171,000
Actuarial loss		0		0
Other comprehensive income (loss), net of tax	524,000	209,000	(1,803,000)	171,000
Comprehensive income	10,383,000	27,917,000	23,652,000	36,154,000
Eliminations [Member]
Net income (loss)	(13,031,000)	(27,231,000)	(34,691,000)	(42,187,000)
Amortization of loss on cash flow hedge	0	0	0	0
Foreign currency translation adjustment	(524,000)	(210,000)	1,803,000	(176,000)
Actuarial loss		(20,000)		(60,000)
Other comprehensive income (loss), net of tax	(524,000)	(230,000)	1,803,000	(236,000)
Comprehensive income	(13,555,000)	(27,461,000)	(32,888,000)	(42,423,000)
Consolidated [Member]
Net income (loss)	38,716,000	42,744,000	90,266,000	100,909,000
Amortization of loss on cash flow hedge	215,000	215,000	646,000	646,000
Foreign currency translation adjustment	524,000	211,000	(1,803,000)	191,000
Actuarial loss		20,000		60,000
Other comprehensive income (loss), net of tax	739,000	446,000	(1,157,000)	897,000
Comprehensive income	$ 39,455,000	$ 43,190,000	$ 89,109,000	$ 101,806,000