Pension and Other Benefit Plans - Asset Allocations (Details) - Pension Plans, Defined Benefit	Mar. 31, 2020	Mar. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Percent of plan assets	100.00%	100.00%
Equity securities
Defined Benefit Plan Disclosure [Line Items]
Percent of plan assets	19.00%	26.00%
Debt securities
Defined Benefit Plan Disclosure [Line Items]
Percent of plan assets	46.00%	45.00%
Alternatives
Defined Benefit Plan Disclosure [Line Items]
Percent of plan assets	31.00%	25.00%
Cash and other
Defined Benefit Plan Disclosure [Line Items]
Percent of plan assets	4.00%	4.00%