Consolidated Balance Sheets (unaudited) (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Accounts receivable, net of allowance for doubtful accounts	$ 3,354	$ 3,581
Redeemable convertible preferred stock, shares authorized	26,876,384	26,876,384
Series A Redeemable Convertible Preferred Stock [Member]
Redeemable convertible preferred stock, par value	$ 0.001	$ 0.001
Redeemable convertible preferred stock - liquidation preference	13,200
Redeemable convertible preferred stock, shares authorized	6,600,000	6,600,000
Redeemable convertible preferred stock, shares issued	6,600,000	6,600,000
Redeemable convertible preferred stock, shares outstanding	6,600,000	6,600,000
Series A1 Redeemable Convertible Preferred Stock [Member]
Redeemable convertible preferred stock, par value	$ 0.001	$ 0.001
Redeemable convertible preferred stock - liquidation preference	3,228
Redeemable convertible preferred stock, shares authorized	1,176,051	1,176,051
Redeemable convertible preferred stock, shares issued	1,176,051	1,176,051
Redeemable convertible preferred stock, shares outstanding	1,176,051	1,176,051
Series B Redeemable Convertible Preferred Stock [Member]
Redeemable convertible preferred stock, par value	$ 0.001	$ 0.001
Redeemable convertible preferred stock - liquidation preference	13,598
Redeemable convertible preferred stock, shares authorized	4,989,308	4,989,308
Redeemable convertible preferred stock, shares issued	4,989,308	4,989,308
Redeemable convertible preferred stock, shares outstanding	4,989,308	4,989,308
Series B1 Redeemable Convertible Preferred Stock [Member]
Redeemable convertible preferred stock, par value	$ 0.001	$ 0.001
Redeemable convertible preferred stock - liquidation preference	5,616
Redeemable convertible preferred stock, shares authorized	2,138,275	2,138,275
Redeemable convertible preferred stock, shares issued	2,138,275	2,138,275
Redeemable convertible preferred stock, shares outstanding	2,138,275	2,138,275
Series C Redeemable Convertible Preferred Stock [Member]
Redeemable convertible preferred stock, par value	$ 0.001	$ 0.001
Redeemable convertible preferred stock - liquidation preference	21,467
Redeemable convertible preferred stock, shares authorized	3,897,084	3,897,084
Redeemable convertible preferred stock, shares issued	3,855,180	3,855,180
Redeemable convertible preferred stock, shares outstanding	3,855,180	3,855,180
Series D Redeemable Convertible Preferred Stock [Member]
Redeemable convertible preferred stock, par value	$ 0.001	$ 0.001
Redeemable convertible preferred stock - liquidation preference	$ 294,115
Redeemable convertible preferred stock, shares authorized	8,075,666	8,075,666
Redeemable convertible preferred stock, shares issued	8,008,842	8,008,842
Redeemable convertible preferred stock, shares outstanding	8,008,842	8,008,842
Common Stock
Common stock, par value (usd per share)	$ 0.001	$ 0.001
Common stock, shares authorized	50,000,000	45,000,000
Common stock, shares issued	7,096,909	7,025,467
Common stock, shares outstanding	7,096,909	7,025,467
Common Class A [Member]
Common stock, par value (usd per share)	$ 0.001	$ 0.001
Pro Forma [Member] | Common Class B [Member]
Common stock, par value (usd per share)	$ 0.001
Common stock, shares authorized	50,000,000
Common stock, shares issued	33,864,565
Common stock, shares outstanding	33,864,565