Operating Leases (Narrative) (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2020 USD ($)
Lessee Lease Description [Line Items]
Operating lease right-of-use assets	$ 674,100
Operating lease liabilities	$ 712,921
Minimum [Member] | Office Space and Office Equipment [Member]
Lessee Lease Description [Line Items]
Operating leases remaining lease term	1 year
Maximum [Member] | Office Space and Office Equipment [Member]
Lessee Lease Description [Line Items]
Operating leases remaining lease term	16 years