Restructuring Expense (Details) (USD $)	3 Months Ended								12 Months Ended				1 Months Ended	132 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2003	Jan. 31, 2003	Dec. 31, 2014	Dec. 31, 2011 sqft	Jan. 01, 2006 sqft
Kendall Square Lease
Area of real estate property (in square feet)															1,100,000
Restructuring Expense	$ 4,164,000	$ 40,843,000	$ (270,000)	$ 6,188,000	$ 27,658,000	$ 12,048,000	$ 776,000	$ 39,000	$ 50,925,000	$ 40,521,000	$ 1,844,000	$ 91,824,000
Cash Payments												(17,816,000)
Non-cash Expense												(4,482,000)
Restructuring Liability												69,526,000
Lease restructuring expense												78,700,000
Lease operating expense												6,000,000
Kendall Square Facility
Kendall Square Lease
Leased area (in square feet)												290,000
Lease term (in years)													15 years
Area of real estate property (in square feet)																120,000
Discount rate, lease restructuring liability (percent)												10.00%
Lease restructuring and other operating lease expense
Kendall Square Lease
Restructuring Expense												84,726,000
Cash Payments												(15,200,000)
Non-cash Expense												0
Restructuring Liability												69,526,000
Employee severance, benefits and related costs
Kendall Square Lease
Restructuring Expense												2,616,000
Cash Payments												(2,616,000)
Non-cash Expense												0
Restructuring Liability												0
Leasehold improvements and asset impairments
Kendall Square Lease
Restructuring Expense												4,482,000
Cash Payments												0
Non-cash Expense												(4,482,000)
Restructuring Liability												0
2003 Restructuring
Kendall Square Lease
Restructuring Expense									(2,937,000)	372,000	1,844,000			59,914,000
Cash Payments									(17,494,000)	(15,255,000)	(14,853,000)			(196,446,000)
Restructuring Liability	11,596,000				19,115,000				11,596,000	19,115,000	23,328,000	69,526,000		11,596,000	26,313,000
Fan Pier Move Restructuring
Kendall Square Lease
Area of real estate property (in square feet)					120,000					120,000
Discount rate, lease restructuring liability (percent)		9.00%
Restructuring Expense									50,864,000	1,198,000
Cash Payments									(18,271,000)	(401,000)
Restructuring Liability	$ 33,390,000				$ 797,000	$ 797,000			$ 33,390,000	$ 797,000	$ 0			$ 33,390,000