Equity Method Investments and Related-Party Transactions - Schedule of Related Party Transactions (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Mar. 31, 2018
Euro Infrastructure Co [Member]
Related Party Transaction [Line Items]
Revenue	$ 1,620	$ 1,945	$ 4,798	$ 7,574
Expense	5,664	1,725	10,254	5,313
Cash received	4,048	2,191	10,102	6,540
Cash paid	6,585	$ 1,407	10,677	$ 5,416
Accounts receivable					$ 3,307
Collections in excess of revenues and deferred revenues	7,438		7,438		3,246
Ducommun Inc. [Member]
Related Party Transaction [Line Items]
Cash paid	8,209		15,188
Accounts payable	$ 4,287		$ 4,287		$ 2,073

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