Pensions and Other Benefits (Details) - USD ($)	Mar. 31, 2019	Mar. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Asset categories:	$ 321,902,000	$ 326,745,000
(Level 1)
Defined Benefit Plan Disclosure [Line Items]
Asset categories:	66,072,000	85,008,000
(Level 2)
Defined Benefit Plan Disclosure [Line Items]
Asset categories:	153,941,000	121,271,000
(Level 3)
Defined Benefit Plan Disclosure [Line Items]
Asset categories:	5,701,000	18,468,000
Fair Value Measured at Net Asset Value Per Share [Member]
Defined Benefit Plan Disclosure [Line Items]
Asset categories:	96,188,000	101,998,000
Equity securities
Defined Benefit Plan Disclosure [Line Items]
Asset categories:	103,017,000	136,777,000
Equity securities | (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Asset categories:	59,703,000	78,344,000
Equity securities | (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Asset categories:	0	0
Equity securities | (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Asset categories:	0	0
Equity securities | Fair Value Measured at Net Asset Value Per Share [Member]
Defined Benefit Plan Disclosure [Line Items]
Asset categories:	43,314,000	58,433,000
Fixed income
Defined Benefit Plan Disclosure [Line Items]
Asset categories:	205,957,000	174,359,000
Fixed income | (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Asset categories:	602,000	0
Fixed income | (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Asset categories:	153,941,000	121,271,000
Fixed income | (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Asset categories:	5,701,000	18,468,000
Fixed income | Fair Value Measured at Net Asset Value Per Share [Member]
Defined Benefit Plan Disclosure [Line Items]
Asset categories:	45,713,000	34,620,000
Real Estate Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Asset categories:	9,978,000	13,230,000
Real Estate Funds [Member] | (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Asset categories:	2,817,000	4,285,000
Real Estate Funds [Member] | (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Asset categories:	0	0
Real Estate Funds [Member] | (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Asset categories:	0	0
Real Estate Funds [Member] | Fair Value Measured at Net Asset Value Per Share [Member]
Defined Benefit Plan Disclosure [Line Items]
Asset categories:	7,161,000	8,945,000
Cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Asset categories:	2,950,000	2,379,000
Cash equivalents | (Level 1)
Defined Benefit Plan Disclosure [Line Items]
Asset categories:	2,950,000	2,379,000
Cash equivalents | (Level 2)
Defined Benefit Plan Disclosure [Line Items]
Asset categories:	0	0
Cash equivalents | (Level 3)
Defined Benefit Plan Disclosure [Line Items]
Asset categories:	0	0
Cash equivalents | Fair Value Measured at Net Asset Value Per Share [Member]
Defined Benefit Plan Disclosure [Line Items]
Asset categories:	$ 0	$ 0