Industry Segment and Geographic Area Data	6 Months Ended
	Sep. 30, 2021
Segments, Geographical Areas [Abstract]
12. Industry Segment and Geographic Area Data	12. Industry Segment and Geographic Area Data     United States   Canada   Consolidated     (Unaudited)     (All amounts are in thousands of U.S. $'s) Quarter Ended September 30, 2021             Total revenues $ 1,576,830 $ 87,424 $ 1,664,254 Depreciation and amortization, net of (gains) on disposal   141,956   1,065   143,021 Interest expense   38,588   957   39,545 Pretax earnings   521,658   17,218   538,876 Income tax expense   124,620   4,358   128,978 Identifiable assets   15,849,380   487,848   16,337,228               Quarter Ended September 30, 2020             Total revenues $ 1,261,235 $ 63,673 $ 1,324,908 Depreciation and amortization, net of (gains) on disposal   144,222   2,193   146,415 Interest expense   39,983   542   40,525 Pretax earnings   340,200   10,819   351,019 Income tax expense   81,624   3,030   84,654 Identifiable assets   13,693,016   430,462   14,123,478       United States   Canada   Consolidated     (Unaudited)     (All amounts are in thousands of U.S. $'s) Six Months Ended September 30, 2021             Total revenues $ 2,973,191 $ 163,919 $ 3,137,110 Depreciation and amortization, net of (gains) on disposal   269,606   (475)   269,131 Interest expense   76,716   2,007   78,723 Pretax earnings   959,607   34,019   993,626 Income tax expense   229,922   8,631   238,553 Identifiable assets   15,849,380   487,848   16,337,228               Six Months Ended September 30, 2020             Total revenues $ 2,204,038 $ 108,107 $ 2,312,145 Depreciation and amortization, net of (gains) on disposal   312,748   5,970   318,718 Interest expense   78,637   1,409   80,046 Pretax earnings   452,149   13,188   465,337 Income tax expense   107,407   3,839   111,246 Identifiable assets   13,693,016   430,462   14,123,478