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	Jun. 30, 2019	Mar. 31, 2019
Schedule of Equity Method Investments [Line Items]
Investment in unconsolidated affiliate	$ 158,868	$ 160,711
Euro Infrastructure Co [Member]
Schedule of Equity Method Investments [Line Items]
Investment in unconsolidated affiliate	158,868	160,711
Less: proportionate share of net assets of Euro Infrastructure Co.	143,429	145,016
Excess carrying value of investment over proportionate share of net assets	15,439	15,695
Euro Infrastructure Co [Member] | Goodwill [Member]
Schedule of Equity Method Investments [Line Items]
Excess carrying value of investment over proportionate share of net assets	22,031	22,476
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	10,068	10,670
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	(17,699)	(18,522)
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	$ 1,039	$ 1,071