Schedule V - AMERCO and Consolidated Subsidiaries, Supplemental Information (for Property-Casualty Insurance Operations), Parenthetical (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Investment Income, Net [Abstract]
Premiums Earned, Net	$ 124,336	$ 211,803	$ 215,913
Property Casualty Insurance Operations [Member] | Amerco [Member]
Investment Income, Net [Abstract]
Written premiums, net	2,800	2,300
Premiums Earned, Net	2,600	1,700
(Gain) Loss on Investments	$ (3,000)	$ (1,700)	$ (2,600)