Schedule V - AMERCO and Consolidated Subsidiaries, Supplemental Information (for Property-Casualty Insurance Operations) (Details) - Property Casualty Insurance Operations [Member] - Amerco [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Supplemental Information For Property And Casualty Insurance Underwriters [Abstract]
Deferred policy acquisition costs
Reserves for unpaid claims and claims adjustment expense	228,970	233,554	244,400
Discount if any, deducted
Unearned premiums	239	70	49
Net earned premiums (1)	60,853	57,100	52,334
Net investment income (2)	9,373	14,079	14,015
Claim and claim adjustment expenses incurred related to current year	19,579	15,749	13,297
Claim and claim adjustment expenses incurred related to prior year	(5,365)	233	107
Amortization of deferred policy acquisition costs
Paid claims and claim adjustment expense	19,228	17,366	17,609
Net premiums written (1)	$ 61,022	$ 57,123	$ 52,324