Consolidated Statements of Cash Flow - USD ($) $ in Thousands	12 Months Ended
	Jul. 31, 2018	Jul. 31, 2017	Jul. 31, 2016
Cash flows from operating activities:
Net Income	$ 418,007	$ 394,261	$ 270,360
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization, including debt cost	79,040	57,441	49,643
Allowance for doubtful accounts	1,142	187	1,175
Impairment of long-lived assets	1,131	19,365	0
Equity in losses of unconsolidated affiliates	750	671	895
Stock-based payment compensation	23,221	20,840	20,864
Loss (gain) on sale of property and equipment	3,240	184	(54)
Deferred income taxes	16,717	19,901	5,740
Changes in operating assets and liabilities, net of effects from acquisitions:
Accounts receivable	(40,335)	(38,542)	(54,213)
Vehicle pooling costs	(3,353)	(1,915)	(4,137)
Inventories	(3,959)	1,294	(2,509)
Prepaid expenses and other current assets	(776)	1,760	(738)
Other assets	70	1,085	4,164
Accounts payable and accrued liabilities	53,320	4,269	48,347
Deferred revenue	(520)	392	983
Income taxes receivable	(8,916)	12,343	(12,649)
Income taxes payable	(3,149)	(333)	2,788
Other liabilities	(587)	(1,145)	1,839
Net cash provided by operating activities	535,069	492,058	332,498
Cash flows from investing activities:
Purchases of property and equipment	(287,910)	(172,178)	(173,917)
Purchases of assets and liabilities in connection with acquisitions, net of cash acquired	(8,787)	(160,812)	0
Proceeds from sale of property and equipment	6,425	765	662
Proceeds from sale of majority-owned subsidiary	1,796	0	0
Investment in unconsolidated affiliate	0	(3,566)	0
Purchases of marketable securities	0	0	(21,119)
Proceeds from sale of marketable securities	0	0	21,498
Net cash used in investing activities	(288,476)	(335,791)	(172,876)
Goodwill impairment losses	21,800	21,800
Cash flows from financing activities:
Proceeds from the exercise of stock options	44,459	31,188	13,240
Proceeds from the issuance of Employee Stock Purchase Plan shares	5,853	4,270	3,369
Repurchases of common stock	0	0	(442,855)
Payments for employee stock-based tax withholdings	(1,115)	(135,433)	(15,039)
Proceeds from the issuance of long-term debt, net of discount	0	0	93,468
Net (repayments) proceeds on revolving loan facility	(231,000)	(7,000)	238,000
Debt offering costs	0	0	(1,179)
Principal payments on long-term debt	0	0	(337,500)
Payments to Noncontrolling Interests	(235)	0	0
Net cash used in financing activities	(182,038)	(106,975)	(448,496)
Effect of foreign currency translation	(135)	4,959	(11,289)
Net increase (decrease) in cash and cash equivalents	64,420	54,251	(300,163)
Cash and cash equivalents at beginning of period	210,100	155,849	456,012
Cash and cash equivalents at end of period	274,520	210,100	155,849
Supplemental disclosure of cash flow information:
Interest paid	20,343	23,221	23,606
Income taxes paid, net of refunds	142,161	$ 14,011	$ 127,981
International [Member]
Adjustments to reconcile net income to net cash provided by operating activities:
Impairment of long-lived assets	$ 1,157