Industry Segment and Geographic Area Data	3 Months Ended
	Jun. 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 June 30, 2021             Total revenues $ 1,396,361 $ 76,495 $ 1,472,856 Depreciation and amortization, net of gains on disposal   127,650   (1,540)   126,110 Interest expense   38,128   1,050   39,178 Pretax earnings   437,949   16,801   454,750 Income tax expense   105,302   4,273   109,575 Identifiable assets   14,661,722   453,160   15,114,882               Quarter Ended June 30, 2020             Total revenues $ 942,803 $ 44,434 $ 987,237 Depreciation and amortization, net of gains on disposal   168,526   3,777   172,303 Interest expense   38,654   867   39,521 Pretax earnings   111,949   2,369   114,318 Income tax expense   25,783   809   26,592 Identifiable assets   13,279,882   432,477   13,712,359