CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012
Cash flows from operating activities:
Net income	$ 94,879	$ 90,095	$ 92,004
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	32,632	33,214	21,549
Share-based compensation	36,362	25,850	21,229
Deferred income taxes	(16,026)	3,671	(7,121)
Tax effect from share-based payment arrangements	6,035	2,887	6,079
Excess tax benefits from share-based payment arrangements	(6,808)	(6,362)	(8,079)
Net amortization of premium on marketable securities	0	8	221
Provision of (benefit from) doubtful accounts	1,485	327	(122)
Net (gain) loss on sales of property and equipment	(10)	351	63
Changes in operating assets and liabilities:
Accounts receivable	(13,649)	1,286	(26,490)
Prepaid expenses and other assets	(1,754)	(822)	802
Accounts payable	3,174	(590)	6,810
Accrued compensation and employee benefits	17,450	(11,729)	11,314
Other liabilities	15,566	1,823	1,455
Deferred revenue	5,698	(3,889)	10,032
Net cash provided by operating activities	175,034	136,120	129,746
Cash flows from investing activities:
Purchases of property and equipment	(12,590)	(24,147)	(25,483)
Purchases of marketable securities	0	0	(48,067)
Proceeds from maturities of marketable securities	0	22,000	131,659
Cash paid for acquisitions, net of cash acquired	(7,253)	(32,874)	(123,631)
Distribution from (purchase of) cost method investees	0	50	(148)
Net cash used in investing activities	(19,843)	(34,971)	(65,670)
Cash flows from financing activities:
Proceeds from revolving line of credit	145,000	30,000	0
Payments on revolving line of credit and other short-term loans	(61,000)	(18,676)	(5,466)
Payments on senior notes	(8,000)	(49,000)	(8,000)
Proceeds from issuance of treasury stock under employee stock plans	6,554	30,256	70,793
Dividends paid	(2,714)	(2,824)	(2,803)
Repurchases of common stock	(217,039)	(82,752)	(191,056)
Excess tax benefits from share-based payment arrangements	6,808	6,362	8,079
Net cash used in financing activities	(130,391)	(86,634)	(128,453)
Effect of exchange rate changes on cash	(2,903)	(2,946)	234
Increase (decrease) in cash and cash equivalents	21,897	11,569	(64,143)
Cash and cash equivalents, beginning of year	83,178	71,609	135,752
Cash and cash equivalents, end of year	105,075	83,178	71,609
Supplemental disclosures of cash flow information:
Cash paid for income taxes, net of refunds of $3,424, $2,471 and $584 during the years ended September 30, 2014, 2013 and 2012, respectively	22,367	24,141	36,852
Cash paid for interest	28,209	31,011	31,421
Supplemental disclosures of non-cash investing and financing activities:
Unsettled repurchases of common stock	0	2,141	0
Purchase of property and equipment included in accounts payable	$ 363	$ 681	$ 641