Income Taxes - Income Tax Expense (Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Expense (Benefit) [Abstract]
Current federal tax expense (benefit)	$ (3)	$ (41)	$ 227
Deferred federal income tax expense (benefit)	(12)	6	3,197
Federal income tax expense (benefit), continuing operations	(15)	(35)	3,424
Current state and local tax expense (benefit)	(59)	36	144
Deferred state and local income tax expense (benefit)	(4)	0	457
State and local income tax expense (benefit), continuing operations	(63)	36	601
Current foreign tax expense (benefit)	1,408	1,857	2,770
Deferred foreign income tax expense (benefit)	(765)	(762)	(1,248)
Foreign income tax expense (benefit), continuing operations	643	1,095	1,522
Current income tax expense (benefit)	1,346	1,852	3,141
Deferred income tax expense (benefit)	(781)	(756)	2,406
Income tax expense	$ 565	$ 1,096	$ 5,547