Segment Information (Revenue And Operating Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Revenue	$ 1,241,824	$ 1,164,039	$ 1,140,533
Cost of Revenue	326,194	329,019	325,665
Gross margin	915,630	835,020	814,868
Sales and marketing	414,524	372,946	367,465
General and administrative	142,981	145,067	145,615
Restructuring and other charges, net	(1,003)	7,942	76,273
Amortization of acquired intangible assets	31,350	32,108	33,198
Operating income (loss)	73,237	40,898	(37,014)
Interest expense	(41,673)	(42,400)	(29,882)
Interest income and other expense, net	(2,908)	96	(296)
Income (loss) before income taxes	28,656	(1,406)	(67,192)
Depreciation and amortization	87,408	86,742	86,554
Operating Segments [Member]
Revenue	1,241,824	1,164,039	1,140,533
Cost of Revenue	524,633	512,315	509,919
Gross margin	717,191	651,724	630,614
Operating Segments [Member] | Software Products [Member]
Revenue	1,088,487	987,316	943,596
Cost of Revenue	387,817	367,224	344,594
Gross margin	700,670	620,092	599,002
Depreciation and amortization	5,100	5,000	4,700
Operating Segments [Member] | Professional Services [Member]
Revenue	153,337	176,723	196,937
Cost of Revenue	136,816	145,091	165,325
Gross margin	16,521	31,632	31,612
Depreciation and amortization	1,600	1,800	2,000
Unallocated [Member]
Sales and marketing	389,631	357,573	352,806
General and administrative	108,095	108,439	108,548
Restructuring and other charges, net	3,764	7,942	76,273
Amortization of acquired intangible assets	58,056	58,729	57,802
Stock-based compensation	82,939	76,708	65,996
Unallocated Operating Expennses	1,469	1,435	6,203
Depreciation and amortization	$ 22,700	$ 21,200	$ 22,100