Financial Information by Geographic Area (Table Text Block)	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
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, 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	United States   Canada   Consolidated     (All amounts are in thousands U.S. $'s) Fiscal Year Ended March 31, 2018             Total revenues $ 3,435,821 $ 165,293 $ 3,601,114 Depreciation and amortization, net of gains on disposal   363,826   8,521   372,347 Interest expense   123,777   2,929   126,706 Pretax earnings   628,901   8,712   637,613 Income tax expense (benefit)   (155,685)   2,715   (152,970) Identifiable assets   10,425,299   322,123   10,747,422