Accounts Payable and Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accounts Payable and Accrued Expenses
Accrued research payables	$ 51,275	$ 45,826	$ 46,300
Accrued compensation and benefits	37,911	34,526
Accrued settlement costs		24,450
Accrued rent	14,821	19,061
Trade payables	20,820	14,474
Deferred revenue	8,057	7,643
Deferred compensation	2,525	3,262
Accrued restructuring	6	3,157
Accrued transaction processing	3,257	3,230
Other	27,823	18,714
Total	$ 166,495	$ 174,343