Geographic Area Data (Summary of Geographic Area Data) (Details) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Mar. 31, 2024
Quarter ended:
Total revenues	$ 1,548,490	$ 1,540,308
Depreciation and amortization, net of (gains) losses on disposals	224,295	146,880
Interest expense	67,218	60,598
Pretax earnings	256,392	338,695
Income tax expense	60,975	81,857
Identifiable assets	19,305,427	18,614,034	$ 19,058,758
United States [Member]
Quarter ended:
Total revenues	1,467,693	1,461,284
Depreciation and amortization, net of (gains) losses on disposals	219,412	148,313
Interest expense	66,749	59,946
Pretax earnings	247,318	327,072
Income tax expense	58,377	78,595
Identifiable assets	18,454,865	17,892,739
Canada [Member]
Quarter ended:
Total revenues	80,797	79,024
Depreciation and amortization, net of (gains) losses on disposals	4,883	1,433
Interest expense	469	652
Pretax earnings	9,074	11,623
Income tax expense	2,598	3,262
Identifiable assets	$ 850,562	$ 721,295