Segments and Other Geographic Information Segment Reporting (Details) - USD ($) $ in Thousands	3 Months Ended																12 Months Ended
	Jul. 31, 2020		Apr. 30, 2020	[1]	Jan. 31, 2020	[1]	Oct. 31, 2019	[1]	Jul. 31, 2019		Apr. 30, 2019	[1]	Jan. 31, 2019	[1]	Oct. 31, 2018	[1]	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2018
Segment Reporting Information [Line Items]
Service revenues and vehicle sales																	$ 2,205,583	$ 2,041,957	$ 1,805,695
Direct Operating Costs																	972,487	888,111	846,868
Cost of vehicle sales																	225,294	255,504	196,461
General and Administrative Expense																	191,703	181,867	176,890
Impairment of long-lived assets																	0	0	1,131
Operating Income (Loss)	$ 205,715	[1]	$ 195,101		$ 209,892		$ 205,391		$ 192,802	[1]	$ 207,494		$ 164,739		$ 151,440		816,099	716,475	584,345
Depreciation, Depletion and Amortization																	101,390	84,895	78,598
Payments to Acquire Productive Assets																	603,674	374,628	296,697
Assets	3,455,261								2,547,617								3,455,261	2,547,617	2,307,698
Goodwill	343,622								333,321								343,622	333,321	337,235
Operating Segments | UNITED STATES | UNITED STATES
Segment Reporting Information [Line Items]
Service revenues and vehicle sales																	1,860,686	1,656,569	1,491,022
Direct Operating Costs																	827,802	751,653	730,865
Cost of vehicle sales																	135,095	112,268	101,130
General and Administrative Expense																	149,012	151,854	144,140
Impairment of long-lived assets																			0
Operating Income (Loss)																	748,777	640,794	514,887
Depreciation, Depletion and Amortization																	90,635	75,135	67,779
Payments to Acquire Productive Assets																	568,472	311,472	255,868
Assets	2,901,158								2,094,592								2,901,158	2,094,592	1,856,058
Goodwill	262,423								256,998								262,423	256,998	256,434
Operating Segments | International [Member] | International [Member]
Segment Reporting Information [Line Items]
Service revenues and vehicle sales																	344,897	385,388	314,673
Direct Operating Costs																	144,685	136,458	116,003
Cost of vehicle sales																	90,199	143,236	95,331
General and Administrative Expense																	42,691	30,013	32,750
Impairment of long-lived assets																			1,131
Operating Income (Loss)																	67,322	75,681	69,458
Depreciation, Depletion and Amortization																	10,755	9,760	10,819
Payments to Acquire Productive Assets																	35,202	63,156	40,829
Assets	554,103								453,025								554,103	453,025	451,640
Goodwill	$ 81,199								$ 76,323								81,199	76,323	80,801
Service revenues
Segment Reporting Information [Line Items]
Service revenues and vehicle sales																	1,947,140	1,755,694	1,578,502
Service revenues | Operating Segments | UNITED STATES | UNITED STATES
Segment Reporting Information [Line Items]
Service revenues and vehicle sales																	1,714,724	1,537,431	1,385,238
Service revenues | Operating Segments | International [Member] | International [Member]
Segment Reporting Information [Line Items]
Service revenues and vehicle sales																	232,416	218,263	193,264
Vehicle sales
Segment Reporting Information [Line Items]
Service revenues and vehicle sales																	258,443	286,263	227,193
Vehicle sales | Operating Segments | UNITED STATES | UNITED STATES
Segment Reporting Information [Line Items]
Service revenues and vehicle sales																	145,962	119,138	105,784
Vehicle sales | Operating Segments | International [Member] | International [Member]
Segment Reporting Information [Line Items]
Service revenues and vehicle sales																	$ 112,481	$ 167,125	$ 121,409

[1] Earnings per share were computed independently for each of the periods presented; therefore, the sum of the earnings per share amounts for the quarters may not equal the total for the year.