Restructuring Liabilities - Narrative (Details) ft² in Thousands	1 Months Ended	3 Months Ended			9 Months Ended		12 Months Ended
	Feb. 28, 2017 position	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2014 facility	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Dec. 31, 2015 USD ($) ft² lease	Dec. 31, 2003	Jun. 30, 2017 USD ($)	Dec. 31, 2016 USD ($)	Jun. 30, 2016 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring (credits) expense		$ 337,000	$ 8,000		$ 13,859,000	$ 1,038,000
Research and Development Restructuring
Restructuring Cost and Reserve [Line Items]
Restructuring and related cost, number of positions eliminated | position	70
Restructuring (credits) expense		(125,000)			12,315,000
Restructuring reserve		2,632,000			2,632,000				$ 3,507,000	$ 0
Kendall Restructuring
Restructuring Cost and Reserve [Line Items]
Restructuring (credits) expense		227,000	30,000		1,054,000	222,000
Lease term (in years)								15 years
Restructuring and related activities, leased office space, maximum percentage used - not more than								50.00%
Restructuring reserve		946,000	3,944,000		946,000	3,944,000	$ 7,944,000		1,990,000	4,328,000	$ 6,388,000
Fan Pier Move Restructuring
Restructuring Cost and Reserve [Line Items]
Restructuring (credits) expense		235,000	90,000		490,000	472,000
Number of facilities decommissioned | facility				3
Number of leases terminated | lease							2
Area of real estate property (in square feet) | ft²							120
Discount rate related to leases (percent)							9.00%
Restructuring reserve		773,000	3,293,000		773,000	3,293,000	$ 5,964,000		$ 1,521,000	$ 3,626,000	4,863,000
Other Restructuring
Restructuring Cost and Reserve [Line Items]
Restructuring (credits) expense			(112,000)			344,000
Restructuring reserve		$ 0	$ 0		$ 0	$ 0	$ 1,450,000				$ 1,233,000