Selected Quarterly Financial Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2016

Quarterly Financial Information Disclosure [Abstract]

Schedule of Quarterly Financial Information

The following table contains quarterly financial information for 2016 and 2015. The Company believes that the following information reflects all normal recurring adjustments necessary for a fair statement of the information for the periods presented. The operating results for any quarter are not necessarily indicative of results for any future period.

	First Quarter			Second Quarter			Third Quarter			Fourth Quarter
	(in thousands, except per share data)
2016
Product revenues, net	$	9,968		$	12,851		$	14,493		$	15,752
License and collaboration revenues		11,313			19,332			12,417			44,057
Other revenues		—			1,498			1,161			1,431
Cost of revenues		711			1,872			1,010			3,319
Research and development expenses		32,882			40,996			32,078			54,961
Selling, general and administrative expenses		17,795			20,680			18,048			24,206
Restructuring expenses		—			—			809			5,047
Net loss		(38,658	)		(50,958	)		(30,275	)		(33,627	)
Net loss attributable to Merrimack Pharmaceuticals, Inc.		(38,473	)		(50,750	)		(30,068	)		(32,449	)
Net loss per share available to common    stockholders—basic and diluted		(0.33	)		(0.40	)		(0.23	)		(0.25	)

	First Quarter			Second Quarter			Third Quarter			Fourth Quarter
	(in thousands, except per share data)
2015
Product revenues, net	$	—		$	—		$	—		$	4,328
License and collaboration revenues		14,842			36,558			16,440			17,090
Cost of revenues		—			—			—			46
Research and development expenses		35,679			42,806			37,763			44,740
Selling, general and administrative expenses		9,189			12,315			16,956			19,335
Net loss		(34,432	)		(22,901	)		(42,386	)		(48,068	)
Net loss attributable to Merrimack Pharmaceuticals, Inc.		(34,759	)		(22,778	)		(42,594	)		(47,826	)
Net loss per share available to common    stockholders—basic and diluted		(0.32	)		(0.21	)		(0.38	)		(0.41	)