Industry Segment and Geographic Area Data (Details) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Mar. 31, 2022
Quarter ended:
Total revenues	$ 1,597,840	$ 1,472,856
Depreciation and amortization, net of (gains) losses on disposals	123,775	126,110
Interest expense	49,799	39,178
Pretax earnings (loss)	441,056	454,750
Income tax expense	107,054	109,575
Identifiable assets	17,831,604	15,114,882	$ 17,299,581
United States [Member]
Quarter ended:
Total revenues	1,510,386	1,396,361
Depreciation and amortization, net of (gains) losses on disposals	120,986	127,650
Interest expense	48,948	38,128
Pretax earnings (loss)	427,538	437,949
Income tax expense	103,613	105,302
Identifiable assets	17,240,646	14,661,722
Canada [Member]
Quarter ended:
Total revenues	87,454	76,495
Depreciation and amortization, net of (gains) losses on disposals	2,789	(1,540)
Interest expense	851	1,050
Pretax earnings (loss)	13,518	16,801
Income tax expense	3,441	4,273
Identifiable assets	$ 590,958	$ 453,160