Income Taxes Income Taxes - Summary of Uncertain Tax Positions (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning Balance	$ 2,884	$ 0	$ 0
Additions of tax positions of the current year	393	0	0
Additions to tax positions of the prior years	0	2,884	0
Reductions of tax positions of the prior years	(872)	0	0
Reductions related to prior tax positions due to foreign currency	(525)	0	0
Expiration of statutes of limitations	(1)	0	0
Ending Balance	$ 1,879	$ 2,884	$ 0