Income Taxes (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Taxes (Textual) [Abstract]
U.S. federal statutory corporate tax rate	35.00%	35.00%	35.00%
Provision for income taxes	$ 88,172	$ 71,396	$ 77,903
Effective tax rate	48.40%	43.40%	40.60%	37.70%
Deferred Tax Liabilities, Gross, Noncurrent	$ 215,300	$ 202,100
Deferred Tax Liabilities, Net, Noncurrent	150,753	141,239
Long-term deferred tax assets	65,800	63,700
Provision for deferred taxes on undistributed earnings	31,700
Foreign earnings potential tax	7,700
No unrecognized tax benefits	0	0
Foreign [Member]
Income Taxes (Textual) [Abstract]
Operating Loss Carryforwards	62,400
Deferred Tax Liabilities, Net, Noncurrent	2,100	$ 9,600
State [Member]
Income Taxes (Textual) [Abstract]
Operating Loss Carryforwards	$ 258,000
Minimum [Member]
Income Taxes (Textual) [Abstract]
Operating Loss Carryforwards, Expiration Dates	Dec. 31, 2016
Maximum [Member]
Income Taxes (Textual) [Abstract]
Operating Loss Carryforwards, Expiration Dates	Dec. 31, 2035