Income Taxes - Components of Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended							6 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current income tax expense (benefit):
Federal												$ 795	$ (781)	$ 3,037
State												(13)	180	53
Foreign												3,797	4,558	4,094
Total current income tax expense												4,579	3,957	7,184
Deferred income tax expense (benefit):
Federal												(565)	(3,385)	1,984
State												840	(90)	1,556
Foreign												(1,154)	(1,129)	533
Total deferred income tax expense												(879)	(4,604)	4,073
Provision (benefit) for income taxes	$ (1,250)	$ 2,468	$ (1,414)	$ (1,536)	$ (243)	$ 625	$ 506	$ 1,053	$ 1,131	$ (197)	$ 889	$ 3,700	$ (647)	$ 11,257