Income Taxes - Deferred Tax Asset Valuation Allowance (Details) - Valuation Allowance of Deferred Tax Assets - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning balance	$ (57,571)	$ (144,701)	$ (40,118)
Valuation allowances established	(2,001)	(260)	0
Changes to existing valuation allowances	(8,043)	85,828	(105,453)
Release of valuation allowances	0	0	2,006
Currency translation	(49)	1,562	(1,136)
Ending balance	$ (67,664)	$ (57,571)	$ (144,701)