(Loss) Income per Share Applicable to Common Stockholders (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Basic net (loss) income per common share:
Net (loss) income	$ 1,732	$ 1,555	$ 550	$ 1,125	$ 1,927	$ 581	$ 338	$ 192	$ 4,962	$ 3,038	$ (2,955)
Less: Preferred stock dividends											(2,168)
Less: Accretion of redeemable convertible preferred stock											(37)
(Loss) income applicable to common stockholders									4,962	3,038	(5,160)
Basic (loss) income per common share (in dollars per share)	$ 0.05	$ 0.04	$ 0.01	$ 0.03	$ 0.05	$ 0.02	$ 0.01	$ 0.01	$ 0.13	$ 0.08	$ (0.31)
Weighted-average common shares outstanding									37,706	36,492	16,412
Diluted net (loss) income per common share:
Net (loss) income	1,732	1,555	550	1,125	1,927	581	338	192	4,962	3,038	(2,955)
Less: Preferred stock dividends											(2,168)
Less: Accretion of redeemable convertible preferred stock											(37)
(Loss) income applicable to common stockholders									$ 4,962	$ 3,038	$ (5,160)
Diluted (loss) income per common share (in dollars per share)	$ 0.04	$ 0.04	$ 0.01	$ 0.03	$ 0.05	$ 0.01	$ 0.01	$ 0.00	$ 0.12	$ 0.08	$ (0.31)
Weighted-average common shares used to compute diluted (loss) income per share									40,472	39,870	16,412