Equity Method Investments and Related-Party Transactions - The Difference Between Carrying Value of Investment in Euro Infrastructure Co. and Proportionate Share of Net Assets of Euro Infrastructure Co. (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Mar. 31, 2020
Schedule of Equity Method Investments [Line Items]
Investment in unconsolidated affiliate	$ 168,787	$ 160,204
Euro Infrastructure Co [Member]
Schedule of Equity Method Investments [Line Items]
Investment in unconsolidated affiliate	168,787	160,204
Less: proportionate share of net assets of Euro Infrastructure Co.	152,231	144,769
Excess carrying value of investment over proportionate share of net assets	16,556	15,435
Euro Infrastructure Co [Member] | Goodwill [Member]
Schedule of Equity Method Investments [Line Items]
Excess carrying value of investment over proportionate share of net assets	22,838	21,777
Euro Infrastructure Co [Member] | Identifiable Intangible Assets [Member]
Schedule of Equity Method Investments [Line Items]
Excess carrying value of investment over proportionate share of net assets	8,231	8,799
Euro Infrastructure Co [Member] | Tangible Assets [Member]
Schedule of Equity Method Investments [Line Items]
Excess carrying value of investment over proportionate share of net assets	(15,504)	(16,142)
Euro Infrastructure Co [Member] | Deferred Income Taxes [Member]
Schedule of Equity Method Investments [Line Items]
Excess carrying value of investment over proportionate share of net assets	$ 991	$ 1,001