Related Party Transactions (Related Party Revenue) (Details) - USD ($) $ in Thousands	12 Months Ended
Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Related party transactions:
Management fees revenue	$ 31,603	$ 30,406	$ 29,148
Revenue from related parties	31,603	30,406	29,148
Blackwater [Member]
Related party transactions:
Management fees revenue	25,512	24,014	23,986
Mercury [Member]
Related party transactions:
Management fees revenue	$ 6,091	$ 6,392	$ 5,162

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