Variable Interest Entities - Narrative (Details) - USD ($)	Mar. 31, 2020	Dec. 31, 2019
Variable Interest Entities
Assets	$ 18,209,659,000	$ 18,287,013,000
Liabilities	10,292,648,000	10,087,120,000
Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entities
Assets	215,962,000	217,451,000
Variable Interest Entity, Primary Beneficiary
Variable Interest Entities
Assets	4,860,033,000	4,923,656,000
Liabilities	$ 2,692,361,000	$ 2,646,623,000