| Income Taxes Income Tax (Tables)
 | 12 Months Ended | 
| Dec. 31, 2016 | 
|---|
| Income Tax Disclosure [Abstract] |  | 
| Schedule of Income before Income Tax, Domestic and Foreign [Table Text Block] | 
|  |  
|  |  |  |  |  |  |  |  |  |  |  |  |  
|   | Years Ended December 31, |  
|   | 2016 |   | 2015 |   | 2014 |  
|   | (in thousands) |  
| Domestic | $ | 75,778 | 
 |   | $ | (44,094 | ) |   | $ | (9,631 | ) |  
| Foreign | (12,088 | ) |   | 1,188 | 
 |   | 886 | 
 |  
| Income (loss) before income taxes | $ | 63,690 | 
 |   | $ | (42,906 | ) |   | $ | (8,745 | ) |  | 
| Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] | 
|  |  
|  |  |  |  |  |  |  |  |  |  |  |  |  
|   | Years Ended December 31, |  
|   | 2016 |   | 2015 |   | 2014 |  
|   | (in thousands) |  
| Current: |   |   |   |   |   |  
| Federal | $ | 1,216 | 
 |   | $ | — | 
 |   | $ | — | 
 |  
| State | (11 | ) |   | 16 | 
 |   | 1 | 
 |  
| Foreign | 1,092 | 
 |   | 942 | 
 |   | 577 | 
 |  
| Total current | 2,297 | 
 |   | 958 | 
 |   | 578 | 
 |  
| Deferred: |   |   |   |   |   |  
| Federal | 17,492 | 
 |   | (13,759 | ) |   | (3,341 | ) |  
| State | (8,271 | ) |   | (1,034 | ) |   | 253 | 
 |  
| Foreign | (2,459 | ) |   | 126 | 
 |   | 54 | 
 |  
| Valuation allowance release due to acquisition | — | 
 |   | (1,757 | ) |   | (2,335 | ) |  
| Change in valuation allowance | (6,661 | ) |   | 14,891 | 
 |   | 3,087 | 
 |  
| Total deferred | 101 | 
 |   | (1,533 | ) |   | (2,282 | ) |  
| Total income tax provision (benefit) | $ | 2,398 | 
 |   | $ | (575 | ) |   | $ | (1,704 | ) |  | 
| Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] | 
|  |  
|  |  |  |  |  |  |  |  |  |  |  |  |  
|   | Years Ended December 31, |  
|   | 2016 |   | 2015 |   | 2014 |  
|   | (in thousands) |  
| Provision (benefit) at statutory rate | $ | 22,294 | 
 |   | $ | (14,588 | ) |   | $ | (2,973 | ) |  
| State income taxes (net of federal benefit) | (13 | ) |   | 275 | 
 |   | (391 | ) |  
| Research and development credits | (9,076 | ) |   | (2,083 | ) |   | (66 | ) |  
| Foreign rate differential | 2,888 | 
 |   | (62 | ) |   | (31 | ) |  
| Stock compensation | (5,756 | ) |   | 549 | 
 |   | 609 | 
 |  
| Foreign deemed dividend | 51 | 
 |   | 279 | 
 |   | — | 
 |  
| Transaction costs | 749 | 
 |   | 1,329 | 
 |   | — | 
 |  
| Uncertain tax positions | (1,204 | ) |   | 600 | 
 |   | 304 | 
 |  
| Foreign tax credits | (72 | ) |   | (144 | ) |   | — | 
 |  
| Permanent and other | (802 | ) |   | 96 | 
 |   | 92 | 
 |  
| Valuation allowance release due to acquisition | — | 
 |   | (1,757 | ) |   | (2,335 | ) |  
| Valuation allowance | (6,661 | ) |   | 14,931 | 
 |   | 3,087 | 
 |  
| Total provision (benefit) for income taxes | $ | 2,398 | 
 |   | $ | (575 | ) |   | $ | (1,704 | ) |  | 
| Schedule of Deferred Tax Assets and Liabilities [Table Text Block] | 
|  |  
|  |  |  |  |  |  |  |  |  
|   | December 31, |  
|   | 2016 |   | 2015 |  
|   | (in thousands) |  
| Deferred tax assets: |   |   |   |  
| Net operating loss carryforwards | $ | 19,524 | 
 |   | $ | 27,996 | 
 |  
| Research and development credits | 58,170 | 
 |   | 48,531 | 
 |  
| Accrued expenses and other | 13,387 | 
 |   | 13,654 | 
 |  
| Accrued compensation | 2,073 | 
 |   | 1,747 | 
 |  
| Stock-based compensation | 3,451 | 
 |   | 4,245 | 
 |  
| Intangible assets | 8,575 | 
 |   | 7,198 | 
 |  
|   | 105,180 | 
 |   | 103,371 | 
 |  
| Less valuation allowance | (100,284 | ) |   | (98,535 | ) |  
|   | 4,896 | 
 |   | 4,836 | 
 |  
| Deferred tax liabilities: |   |   |   |  
| Fixed assets | (2,202 | ) |   | (2,322 | ) |  
| Unremitted foreign earnings | (2,909 | ) |   | (2,628 | ) |  
| Net deferred tax liabilities | $ | (215 | ) |   | $ | (114 | ) |  | 
| Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block] | 
The following table summarizes the changes to the unrecognized tax benefits during 2016, 2015 and 2014:
|  |  
|  |  |  |  |  
|   | (in thousands) |  
| Balance as of December 31, 2013 | $ | 5,462 | 
 |  
| Additions based on tax positions related to the current year | 3,158 | 
 |  
| Additions based on tax positions of prior years | 2,188 | 
 |  
| Balance as of December 31, 2014 | 10,808 | 
 |  
| Additions based on tax positions related to the current year | 2,585 | 
 |  
| Additions related to acquisition | 13,733 | 
 |  
| Decreases based on tax positions of prior year | (1,073 | ) |  
| Balance as of December 31, 2015 | $ | 26,053 | 
 |  
| Additions based on tax positions related to the current year | 2,025 | 
 |  
| Decreases based on tax positions of prior year | (4,661 | ) |  
| Balance as of December 31, 2016 | $ | 23,417 | 
 |  |