Employee Benefit Plans (Narratives) (Details) - USD ($)	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020
Compensation of related costs, Share-based Payments [Abstract]
Employee stock ownership plan (ESOP), compensation expense	$ 23,000,000.0	$ 23,000,000.0	$ 10,300,000
Employee stock ownership plan (ESOP), cash contributions to ESOP			5,600,000
Cash contributions to ESOP non leveraged	$ 23,000,000.0	$ 23,000,000.0	$ 4,000,000.0
Defined Benefit Plan, Assumed Health Care Cost Trend Rates [Abstract]
Defined benefit plan, health care cost trend rate assumed for next fiscal year	4.90%
Defined benefit plan, ultimate health care cost trend rate	4.00%
Post retirement health insurance [Member]
Deferred Compensation Arrangements [Abstract]
Lifetime maximum benefit paid per individual	$ 20,000
Defined Benefit Plan, Assumed Health Care Cost Trend Rates [Abstract]
Defined benefit plan, health care cost trend rate assumed for next fiscal year	5.00%
Post retirement life insurance [Member]
Deferred Compensation Arrangements [Abstract]
Lifetime maximum benefit paid per individual	$ 3,000
Additional benefit requirement amount	$ 100
Defined Benefit Plan, Assumed Health Care Cost Trend Rates [Abstract]
Defined benefit plan, ultimate health care cost trend rate	4.00%