Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reconciliation of Unrecognized Tax Benefits [Rollforward]
Balance at beginning of period	$ (81)	$ (100)	$ (134)
Reductions related to prior year positions	43	19	34
Balance at end of period	$ (38)	$ (81)	$ (100)