Property and Equipment (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2016 USD ($)	Dec. 31, 2013 ft²	Dec. 31, 2015 USD ($)
Property and Equipment
Property and Equipment, gross	$ 140,103		$ 131,269
Less accumulated depreciation and amortization	(47,481)		(45,263)
Property and Equipment, net	92,622		86,006	[1]
Area of laboratory and office building on lease (in square feet) | ft²		190,000
Term of lease		15 years
Minimum monthly lease rental	$ 500
Initial term of lease over which minimum lease rent is required to be payable	10 years
Last term of lease	5 years
Letter of credit for posted for lease facility	$ 15,000
Restricted investments related to direct financing lease	13,900		14,000
Office Equipment
Property and Equipment
Property and Equipment, gross	8,115		6,753
Laboratory Equipment
Property and Equipment
Property and Equipment, gross	33,263		31,296
Computer Equipment
Property and Equipment
Property and Equipment, gross	26,186		22,491
Building And Leasehold Improvements
Property and Equipment
Property and Equipment, gross	$ 72,539		$ 70,729

[1] The condensed consolidated balance sheet at December 31, 2015 has been derived from the audited financial statements at that date.