Consolidated Statements of Cash Flows $ in Thousands	12 Months Ended
	Aug. 31, 2017 USD ($)	Aug. 31, 2016 USD ($)	Aug. 31, 2015 USD ($)
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 258,259	$ 338,815	$ 241,051
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	48,294	38,052	31,349
Stock-based compensation expense	34,183	29,793	26,371
Loss (gain) on sale of business	1,223	(112,453)
Deferred income taxes	4,879	4,528	(969)
Loss (gain) on sale of assets	59	8	(34)
Tax benefits from share-based payment arrangements	(10,331)	(18,205)	(28,948)
Changes in assets and liabilities, net of effects of acquisitions
Accounts receivable, net of reserves	(29,503)	(3,541)	(4,300)
Accounts payable and accrued expenses	(2,226)	5,525	8,123
Accrued compensation	6,427	3,961	3,516
Deferred fees	(229)	700	53
Taxes payable, net of prepaid taxes	7,877	30,270	30,437
Prepaid expenses and other assets	(850)	7	(4,523)
Deferred rent and other non-current liabilities	2,331	13,674	4,322
Other working capital accounts, net	132	6	(6)
Net cash provided by operating activities	320,527	331,140	306,442
CASH FLOWS FROM INVESTING ACTIVITIES:
Acquisition of businesses, net of cash acquired	(303,086)	(262,909)	(34,758)
Proceeds from sale of business, net		153,137
Purchases of investments	(30,757)	(18,137)	(24,264)
Proceeds from sales of investments	23,399	17,241	19,827
Purchases of property, equipment and leasehold improvements, net of proceeds from dispositions	(36,862)	(47,740)	(25,682)
Net cash used in investing activities	(347,306)	(158,408)	(64,877)
CASH FLOWS FROM FINANCING ACTIVITIES
Dividend payments	(80,898)	(74,218)	(66,551)
Repurchase of common stock	(260,978)	(356,828)	(256,217)
Proceeds from debt	640,000	265,000	35,000
Repayment of debt	(365,000)
Sale of business	(1,223)
Debt issuance costs	(438)	(12)	(32)
Proceeds from employee stock plans	50,045	56,851	71,526
Tax benefits from share-based payment arrangements	10,331	18,205	28,948
Net cash used in financing activities	(8,161)	(91,002)	(187,326)
Effect of exchange rate changes on cash and cash equivalents	1,264	(12,237)	(11,703)
Net (decrease) increase in cash and cash equivalents	(33,676)	69,493	42,536
Cash and cash equivalents at beginning of period	228,407	158,914	116,378
Cash and cash equivalents at end of period	194,731	228,407	158,914
Supplemental Disclosure of Cash Flow Information
Cash paid during the year for income taxes, net of refunds	74,788	87,513	64,750
Supplemental Disclosure of Non-Cash Transactions
Dividends declared, not paid	21,853	20,019	18,179
Stock issued for acquisition of business			$ 2,991