Computation of Basic and Diluted Net Loss Per Share Attributable to Common Stockholders (Detail) (USD $) In Thousands, except 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
Schedule Of Earnings Per Share Basic And Diluted [Line Items]
Net income (loss)	$ (25,062)	$ (18,550)	$ (21,598)	$ (18,142)	$ (13,781)	$ (11,488)	$ 49,762	$ (13,127)	$ (83,352)	$ 11,366	$ 19,984
Noncumulative dividends on convertible preferred stock										(11,366)	(18,757)
Undistributed earnings allocated to participating securities											(1,148)
Net income (loss) attributable to common stockholders, basic									(83,352)		79
Adjustment to undistributed earnings allocated to participating securities											48
Net income (loss) attributable to common stockholders, diluted									$ (83,352)		$ 127
Shares used to compute net income (loss) per share attributable to common stockholders:
Weighted average common shares outstanding									22,842,443	1,350,939	1,249,778
Weighted average effect of dilutive stock options										697,928	839,428
Weighted average number of shares outstanding, diluted shares									22,842,443	2,048,867	2,089,206
Net income (loss) per share attributable to common stockholders:
Basic	$ (0.63)	$ (0.53)	$ (1.47)	$ (12.94)	$ (10.02)	$ (8.38)	$ 1.71	$ (10.08)	$ (3.65)		$ 0.06
Diluted	$ (0.63)	$ (0.53)	$ (1.47)	$ (12.94)	$ (10.02)	$ (8.38)	$ 1.67	$ (10.08)	$ (3.65)		$ 0.06