Nature of the Business and Summary of Significant Accounting Policies - Additional Information (Detail)			1 Months Ended			12 Months Ended
	Mar. 27, 2020 USD ($)	Dec. 03, 2019 USD ($)	Jul. 25, 2019 USD ($)	Jul. 12, 2019 USD ($)	May 31, 2019 USD ($)	Dec. 31, 2020 USD ($) Segment Region	Dec. 31, 2019 USD ($)	Nov. 29, 2019 USD ($)	Apr. 15, 2019 USD ($)	Apr. 30, 2017 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Proceeds from maturities and sales of marketable securities							$ 51,500,000
Proceeds on sale of property and equipment							2,025,000
Special cash dividend paid		$ 6,700,000	$ 20,000,000.0
Dividend payable date		Dec. 23, 2019	Sep. 05, 2019
Dividend payable, date of record		Dec. 16, 2019	Aug. 28, 2019
Accumulated deficit						$ 543,637,000	540,609,000
Net loss from continuing operations						3,028,000	21,267,000
Cash in continuing operations for operating activities						4,625,000	31,368,000
Cash, cash equivalents and marketable securities						$ 14,000,000.0
Number of operating segments | Segment						1
Number of geographic regions | Region						1
Original maturities						Three months or less
Silver Creek Pharmaceuticals, Inc. [Member]
Summary Of Significant Accounting Policies [Line Items]
Proceeds from maturities and sales of marketable securities					$ 7,800,000		$ 7,800,000
Silver Creek Pharmaceuticals, Inc. [Member] | Laboratory Equipment [Member]
Summary Of Significant Accounting Policies [Line Items]
Proceeds on sale of property and equipment					$ 1,400,000
Celator Pharmaceuticals Inc [Member]
Summary Of Significant Accounting Policies [Line Items]
Cash payment received	$ 2,300,000
Reimbursement of expenses	200,000
Transaction expenses	$ 400,000
Loan Agreement [Member] | Hercules Capital, Inc [Member] | Term Loan [Member]
Summary Of Significant Accounting Policies [Line Items]
Payoff amount						$ 16,000,000.0			$ 16,000,000.0
Ipsen [Member] | First Line Treatment of Metastatic Adenocarcinoma of Pancreas [Member]
Summary Of Significant Accounting Policies [Line Items]
Contingent milestone payments receivable										$ 225,000,000.0
Ipsen [Member] | After Failure of First Line Chemotherapy [Member]
Summary Of Significant Accounting Policies [Line Items]
Contingent milestone payments receivable										150,000,000.0
Ipsen [Member] | Additional Indication [Member]
Summary Of Significant Accounting Policies [Line Items]
Contingent milestone payments receivable										75,000,000.0
Ipsen [Member] | Ongoing Multi Part Clinical [Member]
Summary Of Significant Accounting Policies [Line Items]
Contingent milestone payments receivable								$ 5,000,000.0
Ipsen [Member] | Asset Sale Agreement [Member] | Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Contingent milestone payments receivable										$ 450,000,000.0
14ner Sale [Member]
Summary Of Significant Accounting Policies [Line Items]
Upfront cash payment received				$ 3,500,000
14ner Sale [Member] | Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Additional payments receivable on achievement of certain milestone events				54,500,000
14ner Sale [Member] | Maximum [Member] | Achievement of the Primary Endpoint in the First Registrational Clinical Study of Either MM-121 or MM-111 [Member]
Summary Of Significant Accounting Policies [Line Items]
Additional payments receivable on achievement of certain milestone events				3,000,000.0
14ner Sale [Member] | Maximum [Member] | Achievement of Various Regulatory Approval and Reimbursement-Based Milestones in the United States, Europe and Japan [Member]
Summary Of Significant Accounting Policies [Line Items]
Additional payments receivable on achievement of certain milestone events				16,500,000
14ner Sale [Member] | Maximum [Member] | Achievement Various Cumulative Worldwide Net Sales Targets Between $100.0 million and $300.0 million for MM-121 and MM-111 [Member]
Summary Of Significant Accounting Policies [Line Items]
Additional payments receivable on achievement of certain milestone events				35,000,000.0
Cumulative worldwide net sales target				$ 300,000,000.0