Stock-Based Compensation - Schedule of Share-based Compensation, Additional Information (Details) (Stock Options and Restricted Stock Units [Member], USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Stock Options and Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average grant date fair value (in usd per share)	$ 2.33	$ 1.58	$ 1.35
Aggregate intrinsic value of options exercised	$ 297	$ 370	$ 9
Total fair value of shares vested	$ 8,231	$ 4,895	$ 3,564