Income Taxes - Schedule of Components of Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Expense Relatedto Net Income [Abstract]
U.S. federal	$ 1,117	$ 210	$ 309
U.S. state	411	406	(75)
Total current	1,528	616	234
U.S. federal	(2,737)	(16,064)	(1,369)
U.S. state	(1,524)	(2,789)	682
Total deferred	(4,261)	(18,853)	(687)
Income tax benefit	$ (2,733)	$ (18,237)	$ (453)