Income Taxes - Additional Information (Detail) - USD ($)
|
12 Months Ended |
|
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
Dec. 31, 2013 |
| Operating Loss Carryforwards [Line Items] |
|
|
|
|
| Cumulative change in ownership |
More than 50% occurs within a three-year period.
|
|
|
|
| Deferred tax assets |
$ 112,647,000
|
$ 120,798,000
|
|
|
| Percentage of cumulative change in ownership |
50.00%
|
|
|
|
| Valuation allowance |
$ 112,647,000
|
120,798,000
|
|
|
| Net operating loss carryforwards related to windfall tax benefits |
1,600,000
|
|
|
|
| Gross unrecognized tax benefits |
17,545,000
|
4,340,000
|
$ 582,000
|
$ 0
|
| Accrual for interest or penalties |
0
|
0
|
|
|
| Interest or penalties expense |
$ 0
|
0
|
$ 0
|
|
| Tax year open to examination |
1998
|
|
|
|
| Domestic Tax Authority [Member] |
|
|
|
|
| Operating Loss Carryforwards [Line Items] |
|
|
|
|
| Operating loss carryforwards |
$ 101,200,000
|
|
|
|
| Research and development credits and other tax credits |
12,200,000
|
|
|
|
| Net operating loss carryforwards |
315,900,000
|
311,300,000
|
|
|
| Federal research and development credit and orphan drug credit carryforwards |
$ 26,300,000
|
26,300,000
|
|
|
| Domestic Tax Authority [Member] | Earliest Tax Year [Member] |
|
|
|
|
| Operating Loss Carryforwards [Line Items] |
|
|
|
|
| Net operating loss carryforwards, expiration year |
2018
|
|
|
|
| Federal research and development credit and orphan drug credit carryforwards, expiration year |
2018
|
|
|
|
| Domestic Tax Authority [Member] | Latest Tax Year [Member] |
|
|
|
|
| Operating Loss Carryforwards [Line Items] |
|
|
|
|
| Net operating loss carryforwards, expiration year |
2036
|
|
|
|
| Federal research and development credit and orphan drug credit carryforwards, expiration year |
2033
|
|
|
|
| State and Local Jurisdiction [Member] |
|
|
|
|
| Operating Loss Carryforwards [Line Items] |
|
|
|
|
| Net operating loss carryforwards |
$ 269,500,000
|
272,800,000
|
|
|
| Federal research and development credit and orphan drug credit carryforwards |
$ 8,800,000
|
$ 8,800,000
|
|
|
| State and Local Jurisdiction [Member] | Earliest Tax Year [Member] |
|
|
|
|
| Operating Loss Carryforwards [Line Items] |
|
|
|
|
| Net operating loss carryforwards, expiration year |
2017
|
|
|
|
| State and Local Jurisdiction [Member] | Latest Tax Year [Member] |
|
|
|
|
| Operating Loss Carryforwards [Line Items] |
|
|
|
|
| Net operating loss carryforwards, expiration year |
2036
|
|
|
|