Income Taxes - Income (Loss) Before Tax (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017		Dec. 31, 2016
Income Tax Disclosure [Abstract]
United States	$ 19,109	$ 34,259		$ 50,651
Non-U.S.	1,892	1,446		930
Income from continuing operations before income taxes	$ 21,001	$ 35,705	[1]	$ 51,581	[1]

[1] See Note 4.