Variable Interest Entities (VIEs) (Narrative) (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Variable Interest Entities
Assets	$ 16,656,793	$ 16,221,822
Liabilities	9,338,792	8,667,400
Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entities
Assets	107,976	224,754
Variable Interest Entity, Primary Beneficiary
Variable Interest Entities
Assets	4,359,069	4,053,841
Liabilities	$ 2,374,525	$ 1,722,719