Industry Segment and Geographic Area Data (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2022	Dec. 31, 2021	Mar. 31, 2022
Quarter ended:
Total revenues	$ 1,375,336	$ 1,404,336	$ 4,676,040	$ 4,541,446
Depreciation and amortization, net of (gains) losses on disposals	121,704	112,660	371,641	381,791
Interest expense	59,041	44,042	166,033	122,765
Pretax earnings (loss)	261,008	371,446	1,165,703	1,365,072
Income tax expense	61,764	89,980	280,442	328,533
Identifiable assets	18,116,328	16,588,078	18,116,328	16,588,078	$ 17,299,581
United States [Member]
Quarter ended:
Total revenues	1,311,117	1,334,131	4,431,570	4,307,322
Depreciation and amortization, net of (gains) losses on disposals	119,864	110,383	365,585	379,989
Interest expense	58,367	43,140	163,792	119,856
Pretax earnings (loss)	253,778	360,449	1,127,685	1,320,056
Income tax expense	59,774	87,135	270,641	317,057
Identifiable assets	17,473,785	16,077,571	17,473,785	16,077,571
Canada [Member]
Quarter ended:
Total revenues	64,219	70,205	244,470	234,124
Depreciation and amortization, net of (gains) losses on disposals	1,840	2,277	6,056	1,802
Interest expense	674	902	2,241	2,909
Pretax earnings (loss)	7,230	10,997	38,018	45,016
Income tax expense	1,990	2,845	9,801	11,476
Identifiable assets	$ 642,543	$ 510,507	$ 642,543	$ 510,507