Period, after year 1, which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

No definition available.

Stock Incentive and Employee Stock Purchase Plans - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Sep. 08, 2011	Nov. 15, 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total intrinsic value of options exercised	$ 0
Total fair value of option awards recognized as expense	3,443,000	7,500,000	5,983,000
Number of shares issued under the ESPP	0	1,086,837	163,142
Employee Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares of common stock issued upon the exercise of stock options	2,500,000
Duration of the options granted	10 years
Rate of options exercisable after one year	25.00%
Total intrinsic value of options exercised	44,000	0	28,000
Expected recognition period	1 year 10 months 24 days
Total fair value of option awards recognized as expense	818,000	1,700,000	2,700,000
Weighted average fair value of option awards granted	$ 1.20	$ 1.97	$ 3.40
Total unrecognized share-based compensation cost	724,000
Employee Stock Options [Member] \| New Hire [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted vesting period	36 months
Employee Stock Options [Member] \| Existing Employee [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted vesting period	36 months
Restricted stock units outstanding [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected recognition period	1 year 10 months 24 days
Total fair value of option awards recognized as expense	2,600,000	3,400,000	2,600,000
Number of RSUs awarded to employees	447,703	1,015,638	903,214
Aggregate fair value of awards	900,000	3,400,000	4,900,000
Unrecognized compensation expense related to non-vested RSUs	3,400,000
Restricted stock units outstanding [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of RSUs price at fair value	$ 1.74	$ 1.28	$ 3.06
Restricted stock units outstanding [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of RSUs price at fair value	$ 4.17	$ 3.58	$ 9.71
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized share-based compensation cost					316,000
Unrecognized compensation expense related to non-vested RSUs		1,000,000
Percentage of lower limit value of common stock	85.00%
Maximum limit of payroll deductions	10.00%
Amount received in cash through employee withholdings	0	1,600,000	470,000
Number of shares issue that the ESPP authorizes for purchase by eligible employees				1,250,111
Total fair value of awards recognized as expenses	$ 0	$ 1,400,000	$ 707,000