Related Party Transactions (Related Party Costs and Expenses) (Details) - Blackwater [Member] - USD ($) $ in Thousands	12 Months Ended
Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Related Party Cost and Expense [Abstract]
U-Haul lease expenses	$ 2,631	$ 2,678	$ 2,684
U-Haul commission expenses	$ 62,066	$ 61,434	$ 58,595

Rental expense for the reporting period incurred under operating leases, including minimum and any contingent rent expense, net of related sublease income.

Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=77902758&loc=d3e41499-112717

Name:	us-gaap_OperatingLeasesRentExpenseNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration