Fair Value Disclosures - Narrative (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Line Items]
Investments excluded from Fair Value Hierarchy, net asset value practical expedient	$ 371	$ 387
Loans Held-for-sale	5,465	4,955
Carrying value of unfunded commitments	349	364
Nonperforming
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Line Items]
Loans Held-for-sale	72	5
Carrying Amount
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Line Items]
Loans Held-for-sale	43	125
Level 3
Fair Value, Assets and Liabilities Measured on Nonrecurring Basis [Line Items]
Loans Held-for-sale	$ 0	$ 0