Leases - Lease Asset and Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
Lessee, Lease, Description [Line Items]
Right-of-use assets - operating leases	$ 156,347	$ 146,000	$ 0
Lease liabilities - operating leases	195,326	$ 178,000	$ 0
SVB Leerink
Lessee, Lease, Description [Line Items]
Right-of-use assets - operating leases	23,300
Lease liabilities - operating leases	$ 32,300