Income Taxes (Schedule Of Deferred Tax Assets And Liabilities) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Income Tax Disclosure [Abstract]
Net operating loss carryforwards	$ 26,462	$ 31,329
Foreign tax credits	0	2,201
Capitalized research and development	34,560	20,999
Pension benefits	14,838	12,296
Prepaid expenses	41,739	30,614
Deferred revenue	9,899	33,886
Stock-based compensation	12,306	11,622
Other reserves not currently deductible	20,986	13,588
Amortization of intangible assets	168,376	96,841
Research and development and other tax credits	49,995	55,760
Fixed assets	45,450	4,364
Capital loss carryforward	31,248	33,024
Deferred interest	10,864	13,057
Other	1,623	1,152
Gross deferred tax assets	468,346	360,733
Valuation allowance	(177,663)	(141,950)	$ (279,700)	$ (235,500)
Total deferred tax assets	290,683	218,783
Acquired intangible assets not deductible	(42,554)	(41,139)
Pension prepayments	(2,532)	(2,362)
Deferred revenue	(19,312)	(6,978)
Unbilled accounts receivable	(31,005)	0
Deferred income	(19,040)	(6,641)
Prepaid commissions	(17,423)	0
Other	(1,866)	(1,686)
Total deferred tax liabilities	(133,732)	(58,806)
Net deferred tax assets	$ 156,951	$ 159,977