Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Aug. 31, 2014	Aug. 31, 2013	Aug. 31, 2012
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 211,543	$ 198,637	$ 188,809
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation and amortization	34,435	35,779	33,779
Stock-based compensation expense	22,891	39,951	21,982
Deferred income taxes	(1,028)	3,175	(3,760)
Gain on sale of assets	(62)	(26)	0
Tax benefits from share-based payment arrangements	(11,955)	(25,225)	(11,159)
Changes in assets and liabilities, net of effects of acquisitions
Accounts receivable, net of reserves	(13,299)	859	2,083
Accounts payable and accrued expenses	(2,903)	3,355	9
Accrued compensation	1,953	(776)	519
Deferred fees	3,594	(1,107)	(2,573)
Taxes payable, net of prepaid taxes	23,309	13,498	4,209
Prepaid expenses and other assets	(1,535)	2,105	(445)
Deferred rent and other non-current liabilities	(1,672)	(2,846)	(905)
Other working capital accounts, net	(248)	2,430	(583)
Net cash provided by operating activities	265,023	269,809	231,965
CASH FLOWS FROM INVESTING ACTIVITIES
Acquisition of businesses, net of cash acquired	(46,873)	(705)	(21,329)
Purchases of investments	(20,415)	(15,613)	(15,000)
Proceeds from maturities of investments	14,323	14,423	0
Purchases of property, equipment and leasehold improvements, net of proceeds from dispositions	(17,743)	(18,517)	(22,520)
Net cash used in investing activities	(70,708)	(20,412)	(58,849)
CASH FLOWS FROM FINANCING ACTIVITIES
Dividend payments	(61,007)	(56,002)	(49,983)
Repurchase of common stock	(279,829)	(332,168)	(153,641)
Proceeds from employee stock plans	52,152	124,537	33,747
Tax benefits from share-based payment arrangements	11,955	25,225	11,159
Net cash used in financing activities	(276,729)	(238,408)	(158,718)
Effect of exchange rate changes on cash and cash equivalents	2,165	(3,406)	(7,039)
Net (decrease) increase in cash and cash equivalents	(80,249)	7,583	7,359
Cash and cash equivalents at beginning of year	196,627	189,044	181,685
Cash and cash equivalents at end of year	116,378	196,627	189,044
Supplemental Disclosure of Cash Flow Information
Cash paid during the year for income taxes, net of refunds	67,152	53,153	73,219
Supplemental Disclosure of Non-Cash Transactions
Dividends declared, not paid	16,299	15,164	13,727
Stock issued for acquisition of business	$ 0	$ 0	$ 3,974