Income Taxes - Valuation Allowances (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at January 1	$ 12,234	$ 13,179	$ 7,832
Charged to costs and expenses	810	(945)	5,347
(Deductions)/Other	0	0	0
Balance at December 31	$ 13,044	$ 12,234	$ 13,179