Employee Benefit Plans - Stock Options Rollforward (Details) - USD ($) $ / shares in Units, shares in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Options
Balance, December 31, 2015, shares	2,965
Granted, shares	1,474
Exercised, shares	(212)
Forfeited, shares	(95)
Expired, shares	(235)
Balance, December 31, 2016, shares	3,897	2,965
Options exercisable at December 31, 2016, shares	2,155
Options vested as of December 31, 2016 and expected to vest after December 31, 2016, shares	3,769
Weighted Average Exercise Price
Balance, December 31, 2015 (usd per share)	$ 3.89
Granted (usd per share)	4.19
Exercised (usd per share)	2.92
Forfeited (usd per share)	3.66
Expired (usd per share)	8.04
Balance, December 31, 2016 (usd per share)	3.81	$ 3.89
Options exercisable at December 31, 2016 (usd per share)	3.80
Options vested as of December 31, 2016 and expected to vest after December 31, 2016 (usd per share)	$ 3.80
Weighted average remaining contractual term (years)	4 years 6 months 30 days	4 years 3 months 35 days
Options exercisable term (years)	3 years 4 months 7 days
Options vested and as and expected to vest after year end (years)	4 years 6 months 12 days
Aggregate Intrinsic Value	$ 3,642,000	$ 442,000
Options exercisable aggregate intrinsic value	2,480
Options vested and expected to vest at year end aggregate intrinsic value	$ 3,571,000