Income Taxes Income tax expense, income tax reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Taxes [Abstract]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate									25.00%	25.00%	25.00%
Income Tax Reconciliation, Income Tax Expense (Benefit), at Federal Statutory Income Tax Rate									$ 18,652	$ 37,173	$ 83,983
Income Tax Reconciliation, Foreign Income Tax Rate Differential									(16,840)	(14,066)	(6,721)
Income Tax Reconciliation, Nondeductible Expense									2,936	2,832	2,807
Income Tax Reconciliation, Change in Deferred Tax Assets Valuation Allowance									(899)	3,625	1,150
Income Tax Reconciliation, State and Local Income Taxes									600	1,133	3,339
Income Tax Reconciliation, Prior Year Income Taxes									2,412	483	(2,973)
Income Tax Reconciliation, Other Adjustments									(604)	(1,205)	(1,570)
Income Tax Reconciliation, Foreign Exchange									3,381	4,358	1,659
Income Tax Reconciliation, Other Reconciling Items									1,110	(575)	(4,369)
Income Tax Expense (Benefit)	$ 3,607	$ 2,081	$ 671	$ 4,389	$ 4,658	$ 9,753	$ 10,075	$ 9,272	$ 10,748	$ 33,758	$ 77,305