Income Taxes - Reconciliation Of Beginning And Ending Amount Of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of period	$ 343	$ 0	$ 0
Additions for tax positions of prior years	0	343	0
Reductions for tax positions of prior years	(25)	0	0
Balance at end of period	$ 318	$ 343	$ 0