Derivative Financial Instruments - Balance Sheet Offsetting, Assets (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Derivative Assets
Gross Amounts of Recognized Assets	$ 314	$ 285
Gross Amounts offset in the Statement of Financial Position	0	0
Net Amounts of Assets Presented in the Statement of Financial Position	314	285
Financial Instruments (Collateral)	(184)	(145)
Cash Collateral Received	(42)	(21)
Net Amount	88	119
Reverse repurchase, securities borrowing, and similar arrangements
Gross Amounts of Recognized Assets	216	227
Gross Amounts offset in the Statement of Financial Position	0	0
Net Amounts of Assets Presented in the Statement of Financial Position	216	227
Financial Instruments (Collateral)	(216)	(227)
Cash Collateral Received	0	0
Net Amount	0	0
Total
Gross Amounts of Recognized Assets	530	512
Gross Amounts offset in the Statement of Financial Position	0	0
Net Amounts of Assets Presented in the Statement of Financial Position	530	512
Financial Instruments (Collateral)	(400)	(372)
Cash Collateral Received	(42)	(21)
Net Amount	88	119
Interest rate swaps
Derivative Assets
Gross Amounts of Recognized Assets	14	0
Gross Amounts offset in the Statement of Financial Position	0	0
Net Amounts of Assets Presented in the Statement of Financial Position	14	0
Derivative Asset, Not Offset, Policy Election Deduction	0	0
Cash Collateral Received	(7)	0
Net Amount	7	0
Foreign exchange forwards and swaps
Derivative Assets
Gross Amounts of Recognized Assets	183	215
Gross Amounts offset in the Statement of Financial Position	0	0
Net Amounts of Assets Presented in the Statement of Financial Position	183	215
Derivative Asset, Not Offset, Policy Election Deduction	(71)	(76)
Cash Collateral Received	(33)	(21)
Net Amount	79	118
Client foreign currency options
Derivative Assets
Gross Amounts of Recognized Assets	2	2
Gross Amounts offset in the Statement of Financial Position	0	0
Net Amounts of Assets Presented in the Statement of Financial Position	2	2
Derivative Asset, Not Offset, Policy Election Deduction	0	(1)
Cash Collateral Received	0	0
Net Amount	2	1
Client interest rate derivatives
Derivative Assets
Gross Amounts of Recognized Assets	115	68
Gross Amounts offset in the Statement of Financial Position	0	0
Net Amounts of Assets Presented in the Statement of Financial Position	115	68
Derivative Asset, Not Offset, Policy Election Deduction	(113)	(68)
Cash Collateral Received	(2)	0
Net Amount	$ 0	$ 0