Income Taxes - Components of Expense and Earnings (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current Income Tax Expense (Benefit) [Abstract]
Federal	$ 6,583	$ 21,265	$ 4,680
State	(1,844)	2,529	518
Foreign	12,114	14,105	12,540
Current Income Tax Expense (Benefit), Total	16,853	37,899	17,738
Deferred Income Tax Expense (Benefit) [Abstract]
Federal	7,859	6,889	4,601
State	(173)	(36)	104
Foreign	511	(3,099)	783
Income Tax Expense (Benefit), Total	25,050	41,653	23,226
Components Of Earnings Before Taxes [Abstract]
Domestic	27,387	10,468	31,175
Foreign	55,711	50,200	52,834
Income before taxes and equity in net income of associated companies	$ 83,098	$ 60,668	$ 84,009