Derivative Financial Instruments - Schedule of Outstanding Hedges: (Notional Amount) (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Derivatives not designated as hedging instruments | Interest rate contracts | Futures
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount of derivative instruments	$ 6,345	$ 8,683
Derivatives not designated as hedging instruments | Foreign exchange contracts | Futures
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount of derivative instruments	1,560	1,550
Derivatives not designated as hedging instruments | Foreign exchange contracts | Forward, swap and spot
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount of derivative instruments	2,414,003	2,267,221
Derivatives not designated as hedging instruments | Foreign exchange contracts | Options purchased
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount of derivative instruments	745	607
Derivatives not designated as hedging instruments | Foreign exchange contracts | Options written
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount of derivative instruments	257	445
Derivatives not designated as hedging instruments | Other derivative contracts | Stable value contracts
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount of derivative instruments	31,094	31,391
Derivatives not designated as hedging instruments | Other derivative contracts | Deferred value awards
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount of derivative instruments	384	300
Derivatives designated as hedging instruments | Interest rate contracts | Swap agreements
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount of derivative instruments	18,659	22,566
Derivatives designated as hedging instruments | Foreign exchange contracts | Forward and swap
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount of derivative instruments	$ 8,924	$ 8,213