Income Taxes - Uncertain Tax Positions (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Uncertain Tax Positions
Balance at beginning of year	$ 343	$ 161	$ 0
Increases for prior positions	37	0	78
Increases for current year positions	721	182	83
Other Increases	0	0	0
Decreases due to settlements	0	0	0
Expiration of the statute of limitations for the assessment of taxes	0	0	0
Other Decreases	0	0	0
Balance at end of year	$ 1,101	$ 343	$ 161