Income Taxes (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Current
Federal									$ 13,163,000	$ 21,040,000	$ 20,310,000
State									2,732,000	4,427,000	3,896,000
Foreign									3,920,000	4,582,000	3,417,000
Deferred
Federal									(544,000)	(574,000)	3,673,000
State									(98,000)	(358,000)	1,726,000
Foreign									830,000	(1,231,000)	217,000
Income tax expense (benefit)	(6,785,000)	9,069,000	11,347,000	6,372,000	818,000	10,052,000	11,754,000	5,263,000	20,003,000	27,886,000	33,239,000
Income and loss from continuing operations before income taxes
Domestic									65,705,000	68,961,000	78,183,000
Foreign									(3,784,000)	9,825,000	(146,000)
Income from continuing operations before taxes	(902,000)	22,045,000	27,206,000	13,573,000	5,766,000	29,432,000	31,247,000	12,341,000	61,921,000	78,786,000	78,037,000
Reconciliations between the statutory federal income tax rates and effective income tax rates
Federal tax rate (as a percent)									35.00%	35.00%	35.00%
State taxes, net of federal benefit (as a percent)									2.90%	3.40%	4.90%
Tax benefit of domestic manufacturing deduction (as a percent)									(2.10%)	(2.50%)	(2.30%)
Change in valuation allowance (as a percent)									6.00%	(0.30%)	3.30%
Difference between United States statutory and foreign local tax rates (as a percent)									2.60%	0.30%	2.00%
Change in uncertain tax position (as a percent)									(0.30%)	0.00%	(0.70%)
Worthless stock deduction on Irish subsidiary									(15.40%)	0.00%	0.00%
Non-deductible goodwill write-off									1.10%	0.00%	0.00%
Non-deductible professional fee									1.30%	0.00%	0.00%
Other (as a percent)									1.20%	(0.50%)	0.40%
Effective tax rate (as a percent)									32.30%	35.40%	42.60%
Additional disclosures
Tax benefit from worthless stock deduction									$ 9,900,000