Accounts Payable and Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounts Payable and Accrued Expenses
Accrued research payables	$ 74,175	$ 51,275	$ 45,800
Accrued compensation and benefits	38,802	37,911
Accrued costs for potential class action lawsuit settlement	18,000
Accrued rent	13,003	14,821
Trade payables	17,436	20,820
Deferred revenue	9,558	8,057
Deferred compensation	1,448	2,525
Accrued restructuring	1,942	6
Accrued transaction processing	5,055	3,257
Other	32,219	27,823
Total	$ 211,638	$ 166,495