Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) (USD $) In Thousands, except Share data, unless otherwise specified	Total	Series A Convertible Preferred Stock	Series A-2 Convertible Preferred Stock	Series B Convertible Preferred Stock	Series C Convertible Preferred Stock	Total Convertible Preferred Stock	Common Stock	Additional Paid-in Capital	Treasury Stock	Note Receivable from Stockholder	Accumulated Deficit	Non-controlling Interest
Balance at Dec. 31, 2010	$ (50,985)	$ 22,263	$ 6,868	$ 13,948	$ 79,890	$ 122,969			$ (4,575)	$ (103)	$ (46,504)	$ 197
Balance (in shares) at Dec. 31, 2010		5,053,000	1,105,000	3,433,000	10,983,000		5,835,000
Increase (Decrease) in Stockholders' Equity
Accretion of convertible preferred stock	(1,633)	258	82	176	1,117	1,633					(1,633)
Issuance of common stock upon conversion of preferred stock	124,602	(22,521)	(6,950)	(14,124)	(81,007)	(124,602)	2	124,600
Issuance of common stock upon conversion of preferred stock (in shares)		(5,053,000)	(1,105,000)	(3,433,000)	(10,983,000)		22,846,000
Issuance of common stock upon initial public offering	48,297						1	48,296
Issuance of common stock upon initial public offering (in shares)							3,847,000
Issuance of common stock upon exercise and conversion of preferred stock warrants	272							272
Issuance of common stock upon exercise and conversion of preferred stock warrants (in shares)							20,000
Issuance of common stock upon exercise of common stock warrants (in shares)							21,000
Issuance of common stock upon exercise of stock options	1,028							1,028
Issuance of common stock upon exercise of stock options (in shares)	1,015,000						1,015,000
Offering costs	(2,596)							(2,596)
Stock-based compensation expense	3,450							3,450
Retirement of treasury stock								(4,575)	4,575
Forgiveness of note receivable from stockholder	103									103
Excess (deficient) tax benefits from stock-based compensation	246							246
Non-controlling interest distributions	(642)											(642)
Net (loss) income	6,937										6,295	642
Balance at Dec. 31, 2011	129,079						3	170,721			(41,842)	197
Balance (in shares) at Dec. 31, 2011							33,584,000
Increase (Decrease) in Stockholders' Equity
Issuance of common stock upon exercise of stock options	2,574						1	2,573
Issuance of common stock upon exercise of stock options (in shares)	1,899,000						1,899,000
Stock-based compensation expense	2,735							2,735
Excess (deficient) tax benefits from stock-based compensation	2,190							2,190
Non-controlling interest distributions	(103)											(103)
Net (loss) income	8,024										7,295	729
Balance at Dec. 31, 2012	144,499						4	178,219			(34,547)	823
Balance (in shares) at Dec. 31, 2012							35,483,000
Increase (Decrease) in Stockholders' Equity
Issuance of common stock under stock incentive plans	599							599
Issuance of common stock under stock incentive plans (in shares)							465,000
Issuance of common stock upon exercise of stock options (in shares)	461,000
Stock-based compensation expense	4,506							4,506
Repurchase and retirement of common stock	(4,848)										(4,848)
Repurchase and retirement of common stock (in shares)	(722,000)						(722,000)
Excess (deficient) tax benefits from stock-based compensation	(397)							(397)
Non-controlling interest distributions	(608)											(608)
Net (loss) income	(3,143)										(3,793)	650
Balance at Dec. 31, 2013	$ 140,608						$ 4	$ 182,927			$ (43,188)	$ 865
Balance (in shares) at Dec. 31, 2013							35,226,000