Related Party Transactions (Related Party Revenue) (Details) - USD ($) $ in Thousands	3 Months Ended
Jun. 30, 2020	Jun. 30, 2019
Related party transactions:
Management fee revenue	$ 7,347	$ 7,156
Revenue from related parties	7,347	7,156
Blackwater [Member]
Related party transactions:
Management fee revenue	6,148	6,249
Mercury [Member]
Related party transactions:
Management fee revenue	$ 1,199	$ 907

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