Stock-Based Compensation - Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2017	Dec. 31, 2016
Employee Stock Option [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Options, grants in period, weighted average grant date fair value (in dollars per share)	$ 3.31
Options outstanding rollforward
Outstanding at January 1, 2017 (in shares)	3,193,668	3,420,385	3,193,668	3,420,385
Granted (in shares)	143,750
Exercised (in shares)	84,467
Forfeited (in shares)	283,500
Expired (in shares)	2,500
Outstanding at March 31, 2017 (in shares)	3,193,668	3,420,385
Exercisable at March 31, 2017 (in shares)			2,158,893
Options, weighted average exercise price
Outstanding at January 1, 2017 (in dollars per share)			$ 6.30	$ 6.26
Granted (in dollars per share)	$ 5.94
Exercised (in dollars per share)	4.52
Forfeited (in dollars per share)	6.20
Expired (in dollars per share)	$ 5.98
Exercisable at March 31, 2017 (in dollars per share)			$ 6.38
Options Intrinsic Value
Options outstanding at January 1, 2017, intrinsic value (in dollars per share)	$ 1,204
Options, exercised, intrinsic value (in dollars per share)	382
Options outstanding at March 31, 2017, intrinsic value (in dollars per share)	$ 1,633	$ 1,204
Options exercisable, at March 31, 2017, intrinsic value (in dollars per share)			$ 837
Options additional disclosures
Outstanding as of March 31, 2017, weighted average remaining contractual term (in years)	4 years 2 months 12 days	4 years 3 months 18 days
Outstanding as of January 1, 2017, weighted average remaining contractual term (in years)	4 years 2 months 12 days	4 years 3 months 18 days
Weighted average remaining contractual term, options exercisable (in dollars per share)	3 years 6 months
Equity Incentive Plan [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Stock options expiration period	7 years
Employee [Member]
Options outstanding rollforward
Granted (in shares)	100,000
Employee Group [Member] | Equity Incentive Plan [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Stock options vesting period	3 years
Director [Member]
Options outstanding rollforward
Granted (in shares)	43,750
Director [Member] | Equity Incentive Plan [Member]
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Stock options vesting period	1 year