Subsequent Events - Shares of Common Stock Issued Upon Conversion of Preferred Stock (Detail) (Subsequent Events [Member]) In Thousands, unless otherwise specified	Jun. 30, 2013
Preferred Stock [Member]
Subsequent Event [Line Items]
Number of shares	8,118
Common Stock [Member]
Subsequent Event [Line Items]
Number of shares	8,631
Series A [Member] | Preferred Stock [Member]
Subsequent Event [Line Items]
Number of shares	557
Series A [Member] | Common Stock [Member]
Subsequent Event [Line Items]
Number of shares	781
Series B [Member] | Preferred Stock [Member]
Subsequent Event [Line Items]
Number of shares	516
Series B [Member] | Common Stock [Member]
Subsequent Event [Line Items]
Number of shares	805
Series C [Member] | Preferred Stock [Member]
Subsequent Event [Line Items]
Number of shares	3,551
Series C [Member] | Common Stock [Member]
Subsequent Event [Line Items]
Number of shares	3,551
Series D [Member] | Preferred Stock [Member]
Subsequent Event [Line Items]
Number of shares	2,430
Series D [Member] | Common Stock [Member]
Subsequent Event [Line Items]
Number of shares	2,430
Series E [Member] | Preferred Stock [Member]
Subsequent Event [Line Items]
Number of shares	1,064
Series E [Member] | Common Stock [Member]
Subsequent Event [Line Items]
Number of shares	1,064