Stockholders' Equity - Summary of Stock Options Outstanding (Detail) (USD $)	12 Months Ended
Dec. 31, 2014
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Options Outstanding and Exercisable Number of Shares of common stock subject to options	8,006,380
Options Outstanding and Exercisable Weighted Average Remaining Contractual Life (In years)	6 years 7 months 13 days
Options Exercisable Number of Shares of common stock subject to options	4,929,932
Options Exercisable Weighted Average Exercise Price	$ 7.21
Range 1 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Lower Range of Exercise Price	$ 2.55
Upper Range of Exercise Price	$ 3.45
Options Outstanding and Exercisable Number of Shares of common stock subject to options	950,512
Options Outstanding and Exercisable Weighted Average Remaining Contractual Life (In years)	4 years 4 months 28 days
Options Exercisable Number of Shares of common stock subject to options	880,721
Options Exercisable Weighted Average Exercise Price	$ 3.37
Range 2 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Lower Range of Exercise Price	$ 3.80
Upper Range of Exercise Price	$ 5.35
Options Outstanding and Exercisable Number of Shares of common stock subject to options	898,399
Options Outstanding and Exercisable Weighted Average Remaining Contractual Life (In years)	5 years 4 days
Options Exercisable Number of Shares of common stock subject to options	874,189
Options Exercisable Weighted Average Exercise Price	$ 5.27
Range 3 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Lower Range of Exercise Price	$ 5.41
Upper Range of Exercise Price	$ 5.41
Options Outstanding and Exercisable Number of Shares of common stock subject to options	985,758
Options Outstanding and Exercisable Weighted Average Remaining Contractual Life (In years)	7 years 10 months 24 days
Options Exercisable Number of Shares of common stock subject to options	436,290
Options Exercisable Weighted Average Exercise Price	$ 5.41
Range 4 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Lower Range of Exercise Price	$ 5.42
Upper Range of Exercise Price	$ 5.42
Options Outstanding and Exercisable Number of Shares of common stock subject to options	50,000
Options Outstanding and Exercisable Weighted Average Remaining Contractual Life (In years)	5 years 2 months 27 days
Options Exercisable Number of Shares of common stock subject to options	50,000
Options Exercisable Weighted Average Exercise Price	$ 5.42
Range 5 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Lower Range of Exercise Price	$ 5.70
Upper Range of Exercise Price	$ 5.70
Options Outstanding and Exercisable Number of Shares of common stock subject to options	804,771
Options Outstanding and Exercisable Weighted Average Remaining Contractual Life (In years)	5 years 11 months 9 days
Options Exercisable Number of Shares of common stock subject to options	804,771
Options Exercisable Weighted Average Exercise Price	$ 5.70
Range 6 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Lower Range of Exercise Price	$ 5.94
Upper Range of Exercise Price	$ 11.03
Options Outstanding and Exercisable Number of Shares of common stock subject to options	809,679
Options Outstanding and Exercisable Weighted Average Remaining Contractual Life (In years)	5 years 1 month 13 days
Options Exercisable Number of Shares of common stock subject to options	713,466
Options Exercisable Weighted Average Exercise Price	$ 6.70
Range 7 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Lower Range of Exercise Price	$ 11.35
Upper Range of Exercise Price	$ 11.88
Options Outstanding and Exercisable Number of Shares of common stock subject to options	59,250
Options Outstanding and Exercisable Weighted Average Remaining Contractual Life (In years)	2 years 4 months 17 days
Options Exercisable Number of Shares of common stock subject to options	38,750
Options Exercisable Weighted Average Exercise Price	$ 11.76
Range 8 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Lower Range of Exercise Price	$ 12.12
Upper Range of Exercise Price	$ 12.12
Options Outstanding and Exercisable Number of Shares of common stock subject to options	942,287
Options Outstanding and Exercisable Weighted Average Remaining Contractual Life (In years)	8 years 11 months 12 days
Options Exercisable Number of Shares of common stock subject to options	234,592
Options Exercisable Weighted Average Exercise Price	$ 12.12
Range 9 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Lower Range of Exercise Price	$ 12.23
Upper Range of Exercise Price	$ 13.99
Options Outstanding and Exercisable Number of Shares of common stock subject to options	750,324
Options Outstanding and Exercisable Weighted Average Remaining Contractual Life (In years)	4 years 7 months 28 days
Options Exercisable Number of Shares of common stock subject to options	548,824
Options Exercisable Weighted Average Exercise Price	$ 13.97
Range 10 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Lower Range of Exercise Price	$ 14.07
Upper Range of Exercise Price	$ 23.02
Options Outstanding and Exercisable Number of Shares of common stock subject to options	1,755,400
Options Outstanding and Exercisable Weighted Average Remaining Contractual Life (In years)	8 years 8 months 1 day
Options Exercisable Number of Shares of common stock subject to options	348,329
Options Exercisable Weighted Average Exercise Price	$ 14.32

Weighted average exercise price as of the balance sheet date for those equity-based payment arrangements exercisable and outstanding.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

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The floor of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range.

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-Publisher FASB

-Name Accounting Standards Codification

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The number of shares reserved for issuance pertaining to the outstanding exercisable stock options as of the balance sheet date in the customized range of exercise prices for which the market and performance vesting condition has been satisfied.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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The number of shares reserved for issuance pertaining to the outstanding stock options as of the balance sheet date for all option plans in the customized range of exercise prices.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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Weighted average remaining contractual term of outstanding stock options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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The ceiling of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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