Stock Based Compensation - Schedule of activity with respect to non-vested stock options (Details) - Non vested equity awards shares in Thousands	12 Months Ended
	Dec. 31, 2017 $ / shares shares
Shares
Balance at January 1, 2016 (in shares) | shares	163
Granted (in shares) | shares	92
Vested (in shares) | shares	(75)
Forfeited and cancelled (in shares) | shares	(22)
Balance at 2017 (in shares) | shares	158
Weighted Average grant- date fair value
Balance at January 1, 2016 (in dollars per share) | $ / shares	$ 5.22
Granted (in dollars per share) | $ / shares	8.61
Vested (in dollars per share) | $ / shares	8.42
Forfeited and cancelled (in dollars per share) | $ / shares	8.34
Balance at 2017 (in dollars per share) | $ / shares	$ 6.49