Equity Method Investments and Related-Party Transactions - Schedule of Related Party Transactions (Detail) - Euro Infrastructure Co [Member] - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Sep. 30, 2020	Sep. 30, 2020	Mar. 31, 2021
Related Party Transaction [Line Items]
Revenue		$ 1,424
Expense	$ 4,004	8,168
Cash received	4,820	8,222
Cash paid	$ 4,886	$ 13,080
Collections in excess of revenues and deferred revenues			$ 6,013

Amount of revenue, fees and commissions earned from transactions between (a) a parent company and its subsidiaries; (b) subsidiaries of a common parent; (c) an entity and trusts for the benefit of employees, for example, but not limited to, pension and profit-sharing trusts that are managed by or under the trusteeship of the entity's management; (d) an entity and its principal, owners, management, or members of their immediate families; and (e) affiliates.

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+ Details