Description of Business and Summary of Significant Accounting Policies - Additional Information (Detail) $ / shares in Units, € in Millions		12 Months Ended
	Jan. 01, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2018 EUR (€)	Dec. 31, 2018 USD ($) $ / shares	Jan. 24, 2018 $ / shares	Jan. 23, 2018 $ / shares	Jan. 01, 2018 USD ($)	Dec. 31, 2017 EUR (€)	Dec. 31, 2017 USD ($) $ / shares	Nov. 30, 2017 USD ($)
Description Of Business And Significant Accounting Policies [Line Items]
Common stock par value (in USD per share) | $ / shares					$ 0.001	$ 0.001	$ 0			$ 0.001
Accumulated deficit					$ 2,224,746,000					$ 2,195,346,000
Available cash and cash equivalents					67,000,000
Bad debt expense			$ 1,700,000
Allowance for doubtful accounts from collaborative arrangements					0					0
Italian VAT receivables					4,500,000					4,800,000
VAT receivable potential payment				€ 4.2	4,800,000
Unrealized foreign exchange gain (loss)		$ (362,000)	0
Leasehold Improvements
Description Of Business And Significant Accounting Policies [Line Items]
Property and equipment useful life		10 years
Minimum | Assets Other Than Leasehold Improvements
Description Of Business And Significant Accounting Policies [Line Items]
Property and equipment useful life		3 years
Maximum | Assets Other Than Leasehold Improvements
Description Of Business And Significant Accounting Policies [Line Items]
Property and equipment useful life		5 years
Silicon Valley Bank | Secured Debt | Loan and Security Agreement
Description Of Business And Significant Accounting Policies [Line Items]
Unrestricted and unencumbered cash required to be held per agreement										16,000,000	$ 16,000,000
CTI Life Sciences Limited
Description Of Business And Significant Accounting Policies [Line Items]
Unrealized foreign exchange gain (loss)		$ (1,500,000)	$ 4,300,000
Intercompany balance, due from CTILS, noncurrent				€ 28.7	$ 32,800,000				€ 26.2	$ 31,400,000
Development Services
Description Of Business And Significant Accounting Policies [Line Items]
Deferred revenue								$ 1,400,000
Aequus Biopharma, Inc
Description Of Business And Significant Accounting Policies [Line Items]
Interest in majority-owned subsidiary				59.70%	59.70%
Aequus Biopharma, Inc | Affiliated Entity
Description Of Business And Significant Accounting Policies [Line Items]
Interest in majority-owned subsidiary				60.00%	60.00%
Subsequent Event | Minimum
Description Of Business And Significant Accounting Policies [Line Items]
Right-of-use assets recognized	$ 4,600,000
Operating lease liabilities recognized	7,000,000
Subsequent Event | Maximum
Description Of Business And Significant Accounting Policies [Line Items]
Right-of-use assets recognized	4,900,000
Operating lease liabilities recognized	7,300,000
Subsequent Event | Accounting Standards Update 2018-11
Description Of Business And Significant Accounting Policies [Line Items]
Cumulative effect adjustment to opening accumulated deficit	$ 1,200,000