Leases (Table Text Block)	3 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2021	Mar. 31, 2021
Leases [Abstract]
Supplemental Balance Sheet Information Related to Leases		As of December 31, 2021     Finance   Operating   Total     (Unaudited)     (In thousands)               Buildings and improvements $ – $ 136,213 $ 136,213 Furniture and equipment   14,732   –   14,732 Rental trailers and other rental equipment   173,940   –   173,940 Rental trucks   1,243,830   –   1,243,830 Right-of-use assets, gross   1,432,502   136,213   1,568,715 Less: Accumulated depreciation   (739,688)   (56,763)   (796,451) Right-of-use assets, net$ 692,814 $ 79,450 $ 772,264	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
Summary of Weighted-average remaining lease terms and Discount rates	Finance leases       December 31,   March 31,       2021   2021       (Unaudited)   Weighted average remaining lease term (years)   3   3   Weighted average discount rate  3.7 % 3.6 %	Operating leases       December 31,   March 31,       2021   2021       (Unaudited)   Weighted average remaining lease term (years)   16   14.7   Weighted average discount rate  4.6 % 4.6 %
Components of Lease Expense		Nine Months Ended     December 31, 2021   December 31, 2020     (Unaudited)     (In thousands)           Operating lease costs $ 24,018 $ 22,564           Finance lease cost:         Amortization of ROU assets $ 90,056 $ 116,002 Interest on lease liabilities   14,290   17,448 Total finance lease cost$ 104,346 $ 133,450
Maturities of Lease Liabilities		Finance leases   Operating leases     (Unaudited) Year ending December 31,   (In thousands)           2022 $ 142,702 $ 23,774 2023   122,157   22,123 2024   85,912   14,404 2025   48,427   4,974 2026   12,197   3,135 Thereafter   –   60,040 Total lease payments   411,395   128,450 Less: imputed interest   (26,890)   (49,116) Present value of lease liabilities$ 384,505 $ 79,334