Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
Cash flows from operating activities:
Net income	$ (54,465)	$ 47,557	$ 160,194
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Stock-based compensation	65,996	50,182	50,889
Depreciation and amortization	86,554	84,433	77,307
Benefit from deferred income taxes	(44,182)	(49,361)	(19,946)
Excess tax benefits realized from stock-based awards	(93)	(24)	(10,428)
Pension settlement loss	0	66,332	0
Other non-cash costs, net	966	157	(760)
Changes in operating assets and liabilities, excluding the effects of acquisitions:
Accounts receivable	52,617	29,723	7,554
Accounts payable and accrued expenses	(14,185)	31,134	(436)
Accrued compensation and benefits	60,944	(56,950)	8,974
Deferred revenue	16,232	8,852	24,998
Accrued income taxes, net of income tax receivable	6,749	(3,536)	19,134
Other current assets and prepaid expenses	4,591	(10,716)	4,417
Other noncurrent assets	1,444	(17,880)	(17,345)
Net cash provided by operating activities	183,168	179,903	304,552
Cash flows from investing activities:
Additions to property and equipment	(26,189)	(30,628)	(25,275)
Acquisitions of businesses, net of cash acquired	(165,802)	(98,411)	(323,525)
Purchases of investments	(45,165)	(11,000)	0
Net cash used by investing activities	(237,156)	(140,039)	(348,800)
Cash flows from financing activities:
Borrowings under credit facility	670,000	185,000	1,386,250
Repayments of borrowings under revolving credit facility	(580,000)	(128,750)	(1,032,500)
Repurchases of common stock	0	(64,940)	(224,915)
Proceeds from issuance of common stock	21	41	877
Excess tax benefits realized from stock-based awards	93	24	10,428
Payments of withholding taxes in connection with vesting of stock-based awards	(20,939)	(29,207)	(26,857)
Credit facility origination costs	(6,855)	0	(7,930)
Contingent consideration	(10,621)	(4,323)	0
Net cash provided (used) by financing activities	51,699	(42,155)	105,353
Effect of exchange rate changes on cash and cash equivalents	6,807	(17,946)	(9,364)
Net increase (decrease) in cash and cash equivalents	4,518	(20,237)	51,741
Cash and cash equivalents, beginning of year	273,417	293,654	241,913
Cash and cash equivalents, end of year	277,935	273,417	293,654
Fair value of contingent consideration recorded for acquisition	$ 16,900	$ 3,800	$ 13,048