Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Unrecognized Tax Benefits [Roll Forward]
Beginning of year balance	$ 613	$ 613	$ 566
Additions for tax positions of prior years	2	0	8
Additions for tax positions of the current year	21	0	39
Reduction for prior year tax positions	(48)	0	0
Reductions for settlements	(545)
End of year balance	$ 43	$ 613	$ 613