Income Taxes - Summary of Tax Effects of Temporary Differences Portions of Company's Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
Net operating losses	$ 41,419	$ 27,046
Tax credits	23,359	12,110
Stock-based compensation	25,208	11,372
Accrued compensation and related expenses	4,061	1,843
Financing obligation- leased facility	29,842	24,122
Other	463	1,462
Total deferred tax assets:	124,352	77,955
Valuation allowance	(81,127)	(34,664)
Total deferred tax assets, net of valuation allowance:	43,225	43,291
Deferred tax liabilities:
Depreciation and amortization	(26,844)	(30,708)
Goodwill	(19,307)	(16,017)
Total deferred tax liabilities:	(46,151)	(46,725)
Total net deferred tax liabilities:	$ (2,926)	$ (3,434)