Related Party Transactions (Related Party Revenue) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Related party transactions:
Management fee revenue	$ 8,747	$ 7,840	$ 17,196	$ 15,187
Revenue from related parties	8,747	7,840	17,196	15,187
Blackwater [Member]
Related party transactions:
Management fee revenue	7,428	6,644	14,608	12,792
Mercury [Member]
Related party transactions:
Management fee revenue	$ 1,319	$ 1,196	$ 2,588	$ 2,395

Amount, including tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value-added and excise.

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+ Details

- Definition

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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