Income Taxes - Effective Income Tax Rate 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 Tax Disclosure [Abstract]
Computed federal income tax expense at statutory rate of 35%									$ 8,885	$ 10,920	$ 11,050
State income taxes									193	698	438
Tax credits									(1,164)	(1,019)	(888)
Production activity deduction									(53)	0	0
Foreign tax rate differential									(3,717)	(3,564)	(1,958)
Uncertain tax positions									597	536	(76)
Deferred compensation insurance assets									(307)	182	(81)
Transaction-related expenses									274	0	0
Other — including the effect of graduated rates									557	(355)	113
Total income tax expense	$ 2,116	$ (978)	$ 2,572	$ 1,555	$ 145	$ 1,842	$ 3,122	$ 2,289	$ 5,265	$ 7,398	$ 8,598