Financial Instruments (Notational Amounts of Derivatives Held) (Details) $ in Millions	Sep. 30, 2021 USD ($)
Foreign exchange contracts
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, notional amount	$ 1,709
Interest rate caps
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, notional amount	8,742
Interest rate caps | Subsidiaries
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, notional amount	3,000
Interest rate swaps
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, notional amount	1,550
Sold
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, notional amount	5,900
Purchase
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Derivative, notional amount	$ 2,900