Equity Method Investments and Related-Party Transactions - Schedule of Related Party Transactions (Detail) - Euro Infrastructure Co [Member] $ in Thousands	3 Months Ended	6 Months Ended
Sep. 30, 2017 USD ($)	Sep. 30, 2017 USD ($)
Related Party Transaction [Line Items]
Revenue	$ 2,177	$ 5,628
Expense	1,757	3,588
Cash received	2,278	4,349
Cash paid	1,989	4,009
Accounts receivable	1,910	1,910
Collections in excess of revenues and deferred revenues	$ 2,971	$ 2,971

For an unclassified balance sheet, amount of receivables arising from transactions with related parties.

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