Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating Loss Carryforwards	$ 30,800								$ 30,800
Expired net operating loss carryforwards	3,900								3,900
Current Federal Tax Expense (Benefit)									17,257	$ 44,350	$ 44,112
Current Foreign Tax Expense (Benefit)									14,629	23,546	25,103
Current State and Local Tax Expense (Benefit)									1,979	4,727	4,903
Current Income Tax Expense (Benefit)									33,865	72,623	74,118
Deferred Federal Income Tax Expense (Benefit)									(2,905)	2,801	4,754
Deferred Foreign Income Tax Expense (Benefit)									2,947	1,675	1,884
Deferred State and Local Income Tax Expense (Benefit)									(149)	206	152
Deferred Income Tax Expense (Benefit)									(107)	4,682	6,790
Income Tax Expense (Benefit)	$ 4,658	$ 9,753	$ 10,075	$ 9,272	$ 20,841	$ 19,909	$ 17,244	$ 19,311	$ 33,758	$ 77,305	$ 80,908