Leases (Details) $ in Thousands		12 Months Ended
	Jul. 01, 2018 Floor	Dec. 31, 2019 USD ($)	Jan. 01, 2019 USD ($)	Dec. 31, 2018 USD ($)
Lessee, Lease, Description [Line Items]
Operating Lease, Cost		$ 41,257
Variable Lease, Cost		8,474
Operating Lease Additional Floors | Floor	7
Operating Lease Additional Floors Commencing on Lease Effective Date | Floor	3
Operating Lease, Payments		20,175
Operating Lease, Incentive Payments Received		18,771
Operating Lease Right-of-Use Assets		199,988		$ 0
Lessee, Additional Payments for Operating Leases Not Yet Commenced		$ 332,771
Minimum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Lease Not yet Commenced, Term of Contract		1 year
Maximum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Lease Not yet Commenced, Term of Contract		16 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 Lease, Cost		$ 4,107
Letter of Credit [Member]
Lessee, Lease, Description [Line Items]
Other Assets		$ 5,536		$ 5,502