Industry Segment and Geographic Area Data (Table Text Block)	3 Months Ended	9 Months Ended
	Dec. 31, 2020	Dec. 31, 2020
Geographic Areas, Long-Lived Assets [Abstract]
Industry Segment and Geographic Area Data	United States   Canada   Consolidated     (Unaudited)     (All amounts are in thousands of U.S. $'s) Quarter Ended December 31, 2020             Total revenues $ 1,114,816 $ 55,166 $ 1,169,982 Depreciation and amortization, net of (gains) losses on disposal   158,844   1,454   160,298 Interest expense   41,378   750   42,128 Pretax earnings   233,163   8,408   241,571 Income tax expense   56,237   2,349   58,586 Identifiable assets   14,020,573   426,732   14,447,305               Quarter Ended December 31, 2019             Total revenues $ 886,731 $ 41,149 $ 927,880 Depreciation and amortization, net of (gains) losses on disposal   174,669   3,979   178,648 Interest expense   39,042   931   39,973 Pretax earnings (losses)   40,606   (277)   40,329 Income tax expense   9,303   94   9,397 Identifiable assets   12,575,914   418,408   12,994,322	United States   Canada   Consolidated     (Unaudited)     (All amounts are in thousands of U.S. $'s) Nine Months Ended December 31, 2020             Total revenues $ 3,318,854 $ 163,273 $ 3,482,127 Depreciation and amortization, net of (gains) losses on disposal   471,592   7,424   479,016 Interest expense   120,015   2,159   122,174 Pretax earnings   685,312   21,596   706,908 Income tax expense   163,644   6,188   169,832 Identifiable assets   14,020,573   426,732   14,447,305               Nine Months Ended December 31, 2019             Total revenues $ 3,008,067 $ 149,276 $ 3,157,343 Depreciation and amortization, net of (gains) losses on disposal   471,535   10,006   481,541 Interest expense   115,523   2,460   117,983 Pretax earnings   411,565   8,832   420,397 Income tax expense   97,951   2,766   100,717 Identifiable assets   12,575,914   418,408   12,994,322