Schedule II - AMERCO and Consolidated Subsidiaries, Valuation and Qualifying Accounts (Details) - Amerco [Member] - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Allowance for doubtful accounts (deducted from trade receivable) [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year	$ 539	$ 585	$ 760
Additions charged to cost and expenses	886	913	967
Additions charged to other accounts
Deductions	(929)	(959)	(1,172)
Balance at year end	496	539	585
Allowance for obsolescence (deducted from inventory) [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year	2,050	1,597	1,384
Additions charged to cost and expenses	3,279	1,218	213
Additions charged to other accounts
Deductions		(765)
Balance at year end	5,329	2,050	1,597
Allowance for LIFO (deducted from inventory) [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year	14,340	13,463	15,019
Additions charged to cost and expenses	1,786	877
Additions charged to other accounts
Deductions			(1,556)
Balance at year end	16,126	14,340	13,463
Allowance for probable losses (deducted from mortgage loans) [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year	493	368	370
Additions charged to cost and expenses	125	125
Additions charged to other accounts
Deductions			(2)
Balance at year end	$ 618	$ 493	$ 368