Variable Interest Entities (VIEs) (Narrative) (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Variable Interest Entities
Assets	$ 17,562,898	$ 18,287,013
Liabilities	9,983,462	10,087,120
Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entities
Assets	222,924	217,451
Variable Interest Entity, Primary Beneficiary
Variable Interest Entities
Assets	5,254,102	4,923,656
Liabilities	$ 2,962,558	$ 2,646,623