Accounts Payable and Accrued Expenses (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Accounts Payable and Accrued Expenses
Accrued research payables	$ 58,383	$ 56,736
Accrued compensation and benefits	23,537	62,271
Trade payables	21,021	19,547
Accrued rent	18,803	19,169
Deferred revenue	14,156	13,836
Deferred compensation	3,755	3,918
Accrued transaction processing	3,335	2,981
Accrued restructuring	1,960	2,224
Other	18,845	18,529
Total	$ 163,795	$ 199,211