Summary of Significant Accounting Policies Recently Adopted Accounting Standards (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
	Oct. 01, 2018	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018	Sep. 30, 2018
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Accounts Receivable, Net, Current		$ 292,567		$ 292,567		$ 347,873
Prepaid expenses and other current assets		171,717		171,717		94,814
Other assets		255,928		255,928		141,761
Deferred Revenue, Current		300,746		300,746		330,689
Deferred revenue, net of current portion		414,437		414,437		434,316
Deferred tax liabilities		51,656		51,656		49,931
Other liabilities		103,214		103,214		93,593
Hosting and professional services		251,111	$ 273,449	510,699	$ 531,428
Product and licensing		97,543	130,446	255,540	255,194
Maintenance and support		60,929	62,298	136,998	126,795
Revenues		409,583	466,193	903,237	913,417
Hosting Cost		153,637	180,257	316,807	351,784
Product and licensing		9,940	14,126	42,690	27,898
Cost of Sales, Maintenance and Support		8,966	9,579	16,727	19,004
Amortization of intangible assets		9,048	13,058	18,805	26,572
Cost of Goods and Services Sold		181,591	217,020	395,029	425,258
Sales and marketing		75,755	74,857	151,114	155,417
(Benefit) provision for income taxes		(958)	$ 1,993	28	$ (76,976)
New Accounting Pronouncement or Change in Accounting Principle, Cumulative Effect of Change on Equity or Net Assets	$ 233,000
Accumulated deficit		(411,000)		(411,000)		$ (740,837)
Deferred Revenue [Domain]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	70,000
Other Assets [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	180,000
Accounts Receivable [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	30,000			27,293
Deferred Project Costs [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	30,000
Deferred Tax Asset [Domain]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	$ 20,000			9,923
Prepaid Expenses and Other Current Assets [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification				(39,059)
Other Assets [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification				(135,321)
Deferred revenue, current [Domain]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification				56,065
Deferred Revenue [Domain]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification				16,154
Other Noncurrent Liabilities [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification				(11,557)
Retained Earnings [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification				(198,019)
ASC 605
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Accounts Receivable, Net, Current		319,860		319,860
Prepaid expenses and other current assets		132,658		132,658
Other assets		120,607		120,607
Deferred Revenue, Current		356,811		356,811
Deferred revenue, net of current portion		430,591		430,591
Deferred tax liabilities		41,733		41,733
Other liabilities		91,657		91,657
Hosting and professional services		264,311		531,935
Product and licensing		124,194		259,463
Maintenance and support		60,500		121,239
Revenues		449,005		912,637
Hosting Cost		154,322		313,554
Product and licensing		16,525		31,245
Cost of Sales, Maintenance and Support		8,247		16,774
Cost of Goods and Services Sold		188,142		380,378
Sales and marketing		73,653		150,534
(Benefit) provision for income taxes		10,131		10,707
Accumulated deficit		(609,019)		(609,019)
Cost of professional services and hosting
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification		13,200		21,236
Cost of product and licensing
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification		26,651		3,923
Cost of maintenance and support
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification		(429)		(15,759)
Sales Revenue, Net [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification		39,422		9,400
Cost, professional services and hosting [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification		685		(3,253)
Cost, product and licensing [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification		6,585		(11,445)
Cost, maintenance and support [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification		(719)		47
Cost, amortization [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification		0		0
Cost of Sales [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification		6,551		(14,651)
Sales and marketing
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification		(2,102)		(580)
Provision (benefit) for income taxes [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification		$ 11,089		$ 10,679