Reconciliation of Income Tax Expense (Benefit) (Detail)	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reconciliation of Effective Tax Rate [Line Items]
Federal income tax at statutory rates	34.00%	34.00%	34.00%
State income tax, net of federal tax benefit	1.00%	5.00%	2.00%
Research and development credits	3.00%	3.00%	3.00%
Stock compensation	(1.00%)	(1.00%)	(4.00%)
Channel rights	(25.00%)	0.00%	0.00%
Other	0.00%	0.00%	(4.00%)
Increase in valuation allowance	(12.00%)	(41.00%)	(31.00%)
Effective tax rate	0.00%	0.00%	0.00%

Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32698-109319

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
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-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(h)(2))
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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-Topic 740
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-URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32687-109319

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-Subparagraph (SAB TOPIC 6.I)
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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to changes in the valuation allowance for deferred tax assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32698-109319

Reference 2: http://www.xbrl.org/2003/role/presentationRef
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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations applicable to state and local income tax expense (benefit), net of federal tax expense (benefit).

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Effective Income Tax Rate Reconciliation Collaboration Agreement

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Schedule of Effective Tax Rate Reconciliation [Line Items]

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