Leases (Table Text Block)	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Leases [Abstract]
Supplemental Balance Sheet Information Related to Leases	As of March 31, 2021     Finance   Operating   Total     (In thousands)               Buildings and improvements $ - $ 132,901 $ 132,901 Furniture and equipment   22,316   -   22,316 Rental trailers and other rental equipment   203,594   -   203,594 Rental trucks   1,494,098   -   1,494,098 Right-of-use assets, gross   1,720,008   132,901   1,852,909 Less: Accumulated depreciation   (842,970)   (40,396)   (883,366) Right-of-use assets, net $ 877,038 $ 92,505 $ 969,543	As of March 31, 2020     Finance   Operating   Total     (In thousands)               Buildings and improvements $ - $ 125,547 $ 125,547 Furniture and equipment   21,113   -   21,113 Rental trailers and other rental equipment   219,581   -   219,581 Rental trucks   1,634,572   -   1,634,572 Right-of-use assets, gross   1,875,266   125,547   2,000,813 Less: Accumulated depreciation   (794,913)   (18,916)   (813,829) Right-of-use assets, net $ 1,080,353 $ 106,631 $ 1,186,984
Summary of Weighted-average remaining lease terms and Discount rates	Financing leases       March 31,       2021   2020   Weighted average remaining lease term (years)   3   4   Weighted average discount rate   3.6 % 3.5 %   F- 39   amerco and consolidated subsidiaries notes to consolidated financial statements - (continued)     Operating leases       March 31,       2021   2020   Weighted average remaining lease term (years)   14.7   14   Weighted average discount rate   4.6 % 4.6 %
Lease costs	Twelve Months Ended March 31,     2021   2020     (In thousands)           Operating lease costs $ 30,551 $ 27,494           Finance lease cost:         Amortization of right-of-use assets $ 150,994 $ 186,860 Interest on lease liabilities   22,405   30,901 Total finance lease cost $ 173,399 $ 217,761
Maturities of Lease Liabilities	Finance leases   Operating leases Year ending March 31,   (In thousands)           2022 $ 179,470 $ 24,288 2023   134,783   22,239 2024   112,732   21,257 2025   78,910   10,151 2026   47,453   4,006 Thereafter   7   62,175 Total lease payments   553,355   144,116 Less: imputed interest   (39,732)   (51,606) Present value of lease liabilities $ 513,623 $ 92,510