Financial Information by Geographic Area (Table Text Block)	12 Months Ended
	Mar. 31, 2021
Geographic Areas, Long-Lived Assets [Abstract]
Industry Segment and Geographic Area Data	United States   Canada   Consolidated     (All amounts are in thousands U.S. $'s) Fiscal Year Ended March 31, 2021             Total revenues $ 4,334,083 $ 207,902 $ 4,541,985 Depreciation and amortization, net of gains on disposal   631,344   10,160   641,504 Interest expense   160,429   3,073   163,502 Pretax earnings   773,030   23,628   796,658 Income tax expense   180,845   4,957   185,802 Identifiable assets   14,212,978   438,628   14,651,606       United States   Canada   Consolidated     (All amounts are in thousands U.S. $'s) Fiscal Year Ended March 31, 2020             Total revenues $ 3,797,849 $ 181,019 $ 3,978,868 Depreciation and amortization, net of gains on disposal   652,110   15,414   667,524 Interest expense   157,595   3,355   160,950 Pretax earnings   372,687   5,437   378,124 Income tax expense (benefit)   (65,842)   1,918   (63,924) Identifiable assets   13,016,942   421,082   13,438,024       United States   Canada   Consolidated     (All amounts are in thousands U.S. $'s) Fiscal Year Ended March 31, 2019             Total revenues $ 3,597,285 $ 171,422 $ 3,768,707 Depreciation and amortization, net of gains on disposal   575,134   7,421   582,555 Interest expense   139,573   2,872   142,445 Pretax earnings   466,175   11,354   477,529 Income tax expense   103,578   3,094   106,672 Identifiable assets   11,526,876   364,837   11,891,713