Income Taxes - Effective Income Tax Expense (Benefit) Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Statutory amount (computed at 21% in 2018 and 35% in 2017 and 2016)	$ (22,398)	$ (1,449)	$ (714)
Re-measurement of deferred tax assets	0	(7,451)	0
Valuation allowance on foreign tax credits	593	1,514	0
State income tax, net of federal benefit	(1,922)	168	94
Permanent differences, other	1,550	505	99
Permanent differences, incentive stock options	(24)	447	224
Valuation allowance, other	10,384	(77)	1,769
Uncertain tax provision	0	1,614	0
Other	(416)	188	109
Unrecognized tax benefit	1,614	1,614	0
Total	$ (12,233)	$ (4,541)	$ 1,581
Consolidated effective tax rate	11.50%	109.70%	(77.50%)