Geographic Area Data (Summary of Geographic Area Data) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2024	Dec. 31, 2023	Mar. 31, 2024
Quarter ended:
Total revenues	$ 1,388,558	$ 1,339,514	$ 4,595,156	$ 4,529,682
Depreciation and amortization, net of (gains) losses on disposals	253,942	180,387	712,937	489,930
Interest expense	76,581	67,450	215,297	191,991
Pretax earnings	89,417	129,773	592,026	826,516
Income tax expense	22,251	30,549	142,645	196,946
Identifiable assets	20,330,165	19,002,576	20,330,165	19,002,576	$ 19,058,758
United States [Member]
Quarter ended:
Total revenues	1,318,694	1,273,821	4,351,865	4,294,310
Depreciation and amortization, net of (gains) losses on disposals	242,717	176,864	688,729	486,262
Interest expense	76,138	66,772	213,811	189,900
Pretax earnings	89,456	125,531	573,375	801,045
Income tax expense	22,180	29,172	137,269	189,802
Identifiable assets	19,416,798	18,225,204	19,416,798	18,225,204
Canada [Member]
Quarter ended:
Total revenues	69,864	65,693	243,291	235,372
Depreciation and amortization, net of (gains) losses on disposals	11,225	3,523	24,208	3,668
Interest expense	443	678	1,486	2,091
Pretax earnings	39	4,242	18,651	25,471
Income tax expense	71	1,377	5,376	7,144
Identifiable assets	$ 913,367	$ 777,372	$ 913,367	$ 777,372