Employee Benefit Plans - ESPP (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
ESPP [Abstract]
Shares issued pursuant to the ESPP	184	175	242
Cash received for the purchase of shares pursuant to the ESPP	$ 417	$ 322	$ 514
Weighted average purchase price per share	$ 2.26	$ 1.84	$ 2.12