Restructuring Liabilities - Activity Related to Restructuring Liability (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Restructuring activities
Restructuring (credits) expense	$ 337,000	$ 8,000	$ 13,859,000	$ 1,038,000
Kendall Restructuring
Restructuring activities
Liability, beginning of the period	1,990,000	6,388,000	4,328,000	7,944,000
Restructuring (credits) expense	227,000	30,000	1,054,000	222,000
Cash payments	(4,003,000)	(5,340,000)	(12,962,000)	(13,104,000)
Cash received from subleases	2,732,000	2,866,000	8,526,000	8,882,000
Liability, end of the period	946,000	3,944,000	946,000	3,944,000
Fan Pier Move Restructuring
Restructuring activities
Liability, beginning of the period	1,521,000	4,863,000	3,626,000	5,964,000
Restructuring (credits) expense	235,000	90,000	490,000	472,000
Cash payments	(3,262,000)	(4,199,000)	(10,578,000)	(10,451,000)
Cash received from subleases	2,279,000	2,539,000	7,235,000	7,308,000
Liability, end of the period	773,000	3,293,000	773,000	3,293,000
Research and Development Restructuring
Restructuring activities
Liability, beginning of the period	3,507,000		0
Restructuring (credits) expense	(125,000)		12,315,000
Cash payments	(750,000)		(7,869,000)
Asset impairments and other non-cash items	0		(1,814,000)
Liability, end of the period	2,632,000		2,632,000
Other Restructuring
Restructuring activities
Liability, beginning of the period		1,233,000		1,450,000
Restructuring (credits) expense		(112,000)		344,000
Cash payments		(1,121,000)		(1,794,000)
Liability, end of the period	$ 0	$ 0	$ 0	$ 0