Components of Income Tax Expense (Benefit) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income Tax Disclosure [Abstract]
Current federal tax benefit	$ 0	$ 0	$ 0	$ (1)
Current state tax provision	0	0	0	2
Total current tax provision	0	0	0	1
Deferred tax (benefit)	(2)	(2)	(3)	(2)
Total (benefit from) provision for income taxes	$ (2)	$ (2)	$ (3)	$ (1)