Geographic Area Data (Summary of Geographic Area Data) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2025	Dec. 31, 2024	Mar. 31, 2025
Quarter ended:
Total revenues	$ 1,415,608	$ 1,388,558	$ 4,766,000	$ 4,595,156
Depreciation and amortization, net of (gains) losses on disposals	332,837	253,942	990,247	712,937
Interest expense	95,527	76,581	268,162	215,297
Pretax earnings	51,580	89,417	270,760	592,026
Income tax expense	14,612	22,251	59,847	142,645
Identifiable assets	21,617,644	20,330,165	21,617,644	20,330,165	$ 20,479,170
United States [Member]
Quarter ended:
Total revenues	1,341,619	1,318,694	4,506,680	4,351,865
Depreciation and amortization, net of (gains) losses on disposals	318,818	242,717	951,681	688,729
Interest expense	94,878	76,138	266,179	213,811
Pretax earnings	48,362	89,456	261,981	573,375
Income tax expense	14,013	22,180	56,866	137,269
Identifiable assets	20,642,541	19,416,798	20,642,541	19,416,798
Canada [Member]
Quarter ended:
Total revenues	73,989	69,864	259,320	243,291
Depreciation and amortization, net of (gains) losses on disposals	14,019	11,225	38,566	24,208
Interest expense	649	443	1,983	1,486
Pretax earnings	3,218	39	8,779	18,651
Income tax expense	599	71	2,981	5,376
Identifiable assets	$ 975,103	$ 913,367	$ 975,103	$ 913,367