Significant Accounting Policies - Revisions to Statements of Changes in Equity (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Jan. 01, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Retained earnings	$ 619,448	$ 566,608	$ 569,215	$ 508,722	$ 420,659
Accumulated other comprehensive loss	(253,741)		(245,937)	(197,974)	(242,548)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	$ 875,982		851,475	852,101	716,493
Previously Reported [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Retained earnings			576,025	511,367	425,972
Accumulated other comprehensive loss			(246,088)	(197,631)	(242,563)
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest			859,502	855,089	721,791
Adjustment [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Retained earnings			(6,810)	(2,645)	(5,313)
Accumulated other comprehensive loss			151	(343)	15
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest			$ (8,027)	$ (2,988)	$ (5,298)