Employee Benefit Plans (Narratives) (Details)	12 Months Ended
	Mar. 31, 2024 USD ($) Age shares	Mar. 31, 2023 USD ($) shares	Mar. 31, 2022 USD ($)
Compensation of related costs, Share-based Payments [Abstract]
Employee stock ownership plan (ESOP), compensation expense	$ 23,900,000	$ 22,100,000	$ 23,000,000
Cash contributions to ESOP non leveraged	$ 23,900,000	$ 22,100,000	$ 23,000,000
Defined Benefit Plan, Assumed Health Care Cost Trend Rates [Abstract]
Defined benefit plan, health care cost trend rate assumed for next fiscal year	5.90%		4.90%
Defined benefit plan, ultimate health care cost trend rate	4.00%		4.00%
Defined benefit plan, year rate reaches ultimate trend rate	2047		2046
Common Stock [Member]
Compensation of related costs, Share-based Payments [Abstract]
Employee stock ownership plan number of non-leveraged shares purchased for allocation | shares	33,954
Nonvoting Common Stock [Member]
Compensation of related costs, Share-based Payments [Abstract]
Employee stock ownership plan number of non-leveraged shares purchased for allocation | shares	365,544	424,484
Post retirement health insurance [Member]
Deferred Compensation Arrangements [Abstract]
Age requirement for retiring | Age	65
Deferred compensation arrangement with individual, requisite service period	20 years
Lifetime maximum benefit paid per individual	$ 20,000
Post retirement life insurance [Member]
Deferred Compensation Arrangements [Abstract]
Age requirement for retiring | Age	65
Deferred compensation arrangement with individual, requisite service period	20 years
Lifetime maximum benefit paid per individual	$ 3,000
Additional benefit requirement amount	$ 100