Organization and Summary of Significant Accounting Policies - Additional Information (Detail)		3 Months Ended
	Jan. 01, 2019 USD ($)	Mar. 31, 2019 USD ($) Segment	Mar. 31, 2018 USD ($)	Dec. 31, 2018 USD ($)
Organization And Summary Of Significant Accounting Policies [Line Items]
Cash and investments in marketable securities		$ 1,844,532,000		$ 1,918,239,000
Senior secured notes		$ 250,000,000
Senior secured notes, maturity date		Oct. 05, 2020
Number of business segment | Segment		1
Accounts receivable from contracts with customers		$ 14,500,000		24,200,000
Accounts receivable for expense reimbursements from collaboration partner		42,894,000		43,213,000
Operating lease, right-of-use assets	$ 83,500,000	83,475,000
Operating lease, lease liabilities	96,200,000	96,673,000
Cumulative effect adjustment to accumulated deficit			$ 12,577,000
Tax provision on unrealized gain on available-for-sale securities, offset by benefit in continuing operations		$ 1,100,000
India
Organization And Summary Of Significant Accounting Policies [Line Items]
Effective income tax rate		29.00%	31.00%
ASC 842 [Member]
Organization And Summary Of Significant Accounting Policies [Line Items]
Cumulative effect adjustment to accumulated deficit	$ 0
Collaboration Partner [Member]
Organization And Summary Of Significant Accounting Policies [Line Items]
Accounts receivable for expense reimbursements from collaboration partner		$ 28,400,000		$ 19,000,000