Employee Benefit Plans - Narrative (Details) - USD ($)	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Retirement Benefits [Abstract]
Employer matching contribution, percentage of match	6.00%
Employees’ capital accumulation plan, total expense recognized	$ 151,000,000.0	$ 136,300,000	$ 126,900,000
Employees’ capital accumulation plan, company-paid contributions	146,500,000	130,900,000	$ 123,900,000
Defined Benefit Plan Disclosure [Line Items]
Long-term disability obligation	$ 10,700,000	11,600,000
Reduction to plan liability		11,200,000
Deferred compensation plans, maximum eligible deferral of compensation percentage	100.00%
Long-term deferred compensation costs	$ 5,900,000	3,200,000
Retired Officers' Bonus Plan
Defined Benefit Plan Disclosure [Line Items]
Deferred compensation arrangement with individual, annual cash award granted per year of service, amount	10,000
Retired Officers' Bonus Plan and Retired Vice-President Bonus Plan | Other Postretirement Benefits Plan
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, funded (unfunded) status of plan	$ 4,800,000	$ 4,600,000