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Stockholders' Equity - Additional Information (Detail) (USD $) | 12 Months Ended |  | 12 Months Ended | 1 Months Ended |  |  | 1 Months Ended |  |  |
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Dec. 31, 2013 | Dec. 31, 2012 | Dec. 31, 2011 | Dec. 31, 2013 2012 Performance Incentive Plan [Member] | Dec. 31, 2013 2012 Performance Incentive Plan [Member] Employee [Member] | Dec. 31, 2013 2012 Performance Incentive Plan [Member] Director [Member] | Dec. 31, 2013 Restricted Stock Units [Member] | Dec. 31, 2013 Employee Stock Purchase Plan [Member] | Dec. 31, 2013 2000 Non-Officer Equity Incentive Plan [Member] | Jan. 31, 2011 Common Shares [Member] | Dec. 31, 2013 Common Shares [Member] | Jan. 24, 2011 Common Shares [Member] | Jan. 28, 2014 Common Shares [Member] Subsequent Event [Member] | Jan. 31, 2014 Common Shares [Member] Subsequent Event [Member] | Dec. 31, 2013 Preferred Stock [Member] | Dec. 31, 2013 Series A Preferred Stock [Member] | Dec. 31, 2012 Series A Preferred Stock [Member] | Dec. 31, 2011 Series A Preferred Stock [Member]
Changes In Equity And Comprehensive Income Line Items [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Preferred stock, shares authorized | 10,000,000 | 10,000,000 |  |  |  |  |  |  |  |  |  |  |  |  | 10,000,000 |  |  |
Preferred stock, par value | $ 0.0001 | $ 0.0001 |  |  |  |  |  |  |  |  |  |  |  |  | $ 0.0001 |  |  |
Preferred stock, shares designated | 0 | 0 |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 | 0 | 3,100,000
Preferred stock, shares issued | 0 | 0 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Preferred stock, shares outstanding | 0 | 0 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock, shares issued | 116,494,000 | 115,259,000 |  |  |  |  |  |  |  |  |  | 19,000,000 | 9,775,000 |  |  |  |  |
Proceeds from sale of common stock |  |  | $ 219,783,000 |  |  |  |  |  |  | $ 220,400,000 |  |  | $ 117,200,000 | $ 117,200,000 |  |  |  |
Legal, accounting fees, filing fees and other offering expenses |  |  |  |  |  |  |  |  |  | 600,000 |  |  | 600,000 | 600,000 |  |  |  |
Common stock, shares reserved for issuance in equity compensation plans |  |  |  |  |  |  |  |  |  |  | 28,609,480 |  |  |  |  |  |  |
Additional new shares available for award grants |  |  |  | 5,300,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Service period for stock options granted |  |  |  |  | 4 years | 1 year |  |  |  |  |  |  |  |  |  |  |  |
Number of common stock shares available for stock options grants |  |  |  | 10,347,140 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Share-based compensation plan's share limit reduction for every one restricted stock unit granted |  |  |  | 1.5 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Maximum term of stock options under equity incentive plans |  |  |  | 8 years |  |  |  |  |  |  |  |  |  |  |  |  |  |
Maximum term of stock options under equity incentive plans |  |  |  |  |  |  |  |  | 8 years |  |  |  |  |  |  |  |  |
Restricted Stock Units outstanding | 0 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
RSU awards par value | $ 0.0001 | $ 0.0001 |  |  |  |  | $ 0.01 |  |  |  |  |  |  |  |  |  |  |
Restricted stock units award depletion ratio | 1:1.5 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stock, shares authorized | 300,000,000 | 300,000,000 |  |  |  |  |  | 1,500,000 |  |  |  |  |  |  |  |  |  |
Percentage of purchase price of stock |  |  |  |  |  |  |  | 85.00% |  |  |  |  |  |  |  |  |  |
Maximum 401(k) per employee, percentage of annual salary | 60.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Matching 401(k) employer contribution, maximum amount | 3,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Compensation expense in connection with 401(k) retirement plan | $ 1,000,000 | $ 900,000 | $ 900,000 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Severance payment period for executives | 12 months |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Severance payment period for employees | 6 months |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Cash severance payment for chief executive officer | 24 months base salary plus annual target incentive pay |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |

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