Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Deferred tax assets:
Federal and state net operating loss carryforwards	$ 162,521	$ 25,665
Share-based compensation	45,969	12,680
Goodwill	825	1,355
Depreciation and amortization	3,090
Start-up and organizational costs	369	430
Research and development credits	21,157	6,493
Other tax credits	1,358
Accruals and reserves	3,338	2,339
Deferred rent	5,228	4,248
Other deferred tax assets	550	167
Total deferred tax assets	244,405	53,377
Deferred tax liabilities:
Website and software development costs	(13,851)	(7,263)
Intangibles	(200,082)	(6,052)
Other deferred tax liabilities	(52)
Depreciation and amortization		(2,838)
Net deferred tax assets before valuation allowance	30,420	37,224
Less: valuation allowance	(162,715)	$ (37,224)
Net deferred tax assets (liabilities)	$ (132,295)