Financial Information by Geographic Area (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Fiscal year ended:
Total revenues	$ 3,768,707	$ 3,601,114	$ 3,421,767
Depreciation and amortization, net of (gains) losses on disposals	582,555	372,347	471,653
Interest expense	142,445	126,706	113,406
Pretax earnings	477,529	637,613	628,358
Income tax expense	106,672	(152,970)	229,934
Identifiable assets	11,891,713	10,747,422	9,405,840
United States [Member]
Fiscal year ended:
Total revenues	3,597,285	3,435,821	3,271,563
Depreciation and amortization, net of (gains) losses on disposals	575,134	363,826	466,378
Interest expense	139,573	123,777	112,834
Pretax earnings	466,175	628,901	609,589
Income tax expense	103,578	(155,685)	225,278
Identifiable assets	11,526,876	10,425,299	9,030,528
Canada [Member]
Fiscal year ended:
Total revenues	171,422	165,293	150,204
Depreciation and amortization, net of (gains) losses on disposals	7,421	8,521	5,275
Interest expense	2,872	2,929	572
Pretax earnings	11,354	8,712	18,769
Income tax expense	3,094	2,715	4,656
Identifiable assets	$ 364,837	$ 322,123	$ 375,312