Benefit Plans (Narrative) (Details) - USD ($)		9 Months Ended
	May 31, 2021	Sep. 30, 2021
Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, contributions by employer		$ 23,000,000
Pension [Member] | Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Anticipated additional employer contributions		5,000,000
Postretirement [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, contributions by employer		0
Decrease in accrued postretirement health care cost liability	$ 432,000,000
Postretirement [Member] | Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Anticipated additional employer contributions		$ 0