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Stock-Based Compensation - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified | 12 Months Ended |  | 12 Months Ended |  |  | 12 Months Ended |
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Dec. 31, 2013 | Dec. 31, 2012 | Dec. 31, 2011 | Dec. 31, 2013 Stock Options | Dec. 31, 2013 Restricted Stock Units (RSUs) | Dec. 31, 2012 Restricted Stock Units (RSUs) | Dec. 31, 2011 Restricted Stock Units (RSUs) | Dec. 31, 2013 Employee Stock Purchase Plan | Dec. 31, 2012 Employee Stock Purchase Plan | Dec. 31, 2011 Employee Stock Purchase Plan | Jun. 06, 2012 Employee Stock Purchase Plan | Dec. 31, 2013 Employee Stock Purchase Plan Maximum | Dec. 31, 2013 2008 Equity Incentive Plan | Jun. 12, 2013 2008 Equity Incentive Plan | Jun. 06, 2012 2008 Equity Incentive Plan | Dec. 31, 2013 2008 Equity Incentive Plan Stock Options | Dec. 31, 2013 2008 Equity Incentive Plan Performance-based Stock or Cash Awards | Dec. 31, 2013 2008 Equity Incentive Plan Maximum | Jun. 06, 2012 2008 Equity Incentive Plan Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Employee Stock Purchase Plan, offering period |  |  |  |  |  |  |  |  |  |  |  | 27 months |  |  |  |  |  |  |
Employee Stock Purchase Plan, period for eligible employees to purchase |  |  |  |  |  |  |  |  |  |  |  | 6 months |  |  |  |  |  |  |
Employee Stock Purchase Plan, purchase price of common stock as percentage of fair market value |  |  |  |  |  |  |  | 85.00% |  |  |  |  | 100.00% |  |  |  |  |  |
Employee Stock Purchase Plan, authorized shares for issuance |  |  |  |  |  |  |  |  |  | 820,500 |  |  |  |  |  |  | 500,000 |  |
Increase in shares of common stock authorized for issuance |  |  |  |  |  |  |  |  |  |  | 500,000 |  |  | 6,000,000 | 3,000,000 |  |  |  |
Maximum number of shares of common stock authorized for issuance | 112,500,000 | 112,500,000 |  |  |  |  |  |  |  |  | 1,320,500 |  |  |  |  |  |  |  | 19,540,940
Number of shares available for future issuance |  |  |  |  |  |  |  | 514,820 |  |  |  |  | 8,100,000 |  |  |  |  |  |
Stock-based compensation, award term |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 10 years |
Stock-based compensation, vesting period |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 4 years |  |  |
Stock option plan granted on cash award |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 1.0 |  |
Performance-based stock options, outstanding |  |  |  |  |  |  |  |  |  |  |  |  | 0 |  |  |  |  |  |
Aggregate number of shares of common stock reserved for future issuance | 18,600,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Outstanding options and other stock based awards | 10,500,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Total intrinsic value of options exercised | 0.6 | 0.3 | 0.2 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Restricted stock units vesting Description |  |  |  |  | The restricted stock units generally vest in three annual installments from the date of grant and are generally issuable at the end of the three-year vesting term. |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fair value of restricted stock units which vested during the year |  |  |  |  | 0.05 | 0.05 | 0.10 |  |  |  |  |  |  |  |  |  |  |  |
Stock-based compensation expense expected to be recognized |  |  |  | $ 5.9 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stock-based compensation, weighted average recognition period |  |  |  | 2 years 6 months 22 days |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Stock-based compensation, expected dividend yield | 0.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Weighted average grant-date fair value of stock options granted | $ 2.03 | $ 2.13 | $ 1.37 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Weighted average grant-date fair value of awards granted |  |  |  |  |  | $ 3.03 |  | $ 1.18 | $ 1.43 | $ 0.68 |  |  |  |  |  |  |  |  |

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- Definition Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, 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 -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (i) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Description of award terms as to how many shares or portion of an award are no longer contingent on satisfaction of either a service condition, market condition or a performance condition, thereby giving the employee the legal right to convert the award to shares, to sell the shares, and be entitled to the cash proceeds of such sale. For example, vesting may be expressed as being 25 percent of the shares under option on each anniversary of the grant date. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2)(iii)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d)(2) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2)(iii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d)(2) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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