Risk Management - Interest Rate Risk Management (Details) $ in Millions	Jun. 30, 2020 USD ($)
Fixed-to-Variable Interest Rate Contracts | Fair Value Hedging
Derivative [Line Items]
Notional amount	$ 8,025
Floating-to-Fixed Interest Rate Contracts | Fair Value Hedging
Derivative [Line Items]
Notional amount	2,500
Floating-to-Fixed Interest Rate Contracts | Derivatives in cash flow hedging relationships
Derivative [Line Items]
Notional amount	250
Current Portion Of Debt | Fixed-to-Variable Interest Rate Contracts
Derivative [Line Items]
Derivative, Amount of Hedged Item	1,300
Long-term Debt | Fixed-to-Variable Interest Rate Contracts
Derivative [Line Items]
Derivative, Amount of Hedged Item	$ 6,725