Leases (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Jan. 01, 2019	Dec. 31, 2018
Lessee, Lease, Description [Line Items]
Operating Leases, Rent Expense	$ 12,221	$ 10,454	$ 23,256	$ 20,571
Operating Lease, Payments			8,485
Operating Lease, Incentive Payments Received			10,062
Operating Lease Right-of-Use Assets	178,241		178,241			$ 0
Lessee, Additional Payments for Operating Leases Not Yet Commenced	252,274		252,274
Letter of Credit [Member]
Lessee, Lease, Description [Line Items]
Other Assets	5,518		5,518			$ 5,502
Office Equipment [Member]
Lessee, Lease, Description [Line Items]
Operating Leases, Rent Expense	$ 1,004	$ 799	$ 1,927	$ 1,259
Minimum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Lease Not yet Commenced, Term of Contract	7 years		7 years
Maximum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Lease Not yet Commenced, Term of Contract	15 years		15 years
Accounting Standards Update 2016-02 [Member]
Lessee, Lease, Description [Line Items]
Operating Lease Right-of-Use Assets					$ 180,935