Leases (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Jan. 01, 2019	Dec. 31, 2018
Lessee, Lease, Description [Line Items]
Operating Leases, Rent Expense	$ 11,769	$ 11,470	$ 35,025	$ 32,042
Operating Lease, Payments			15,778
Operating Lease, Incentive Payments Received			12,854
Operating Lease Right-of-Use Assets	183,083		183,083			$ 0
Lessee, Additional Payments for Operating Leases Not Yet Commenced	$ 255,185		$ 255,185
Minimum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Lease Not yet Commenced, Term of Contract	3 years		3 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
Office Equipment [Member]
Lessee, Lease, Description [Line Items]
Operating Leases, Rent Expense	$ 1,132	$ 939	$ 3,059	$ 2,198
Letter of Credit [Member]
Lessee, Lease, Description [Line Items]
Other Assets	$ 5,527		$ 5,527			$ 5,502