Subsequent Events (Details) - USD ($) shares in Thousands		1 Months Ended	12 Months Ended
	Nov. 01, 2019	Nov. 15, 2019	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017	Sep. 13, 2018
Subsequent Event [Line Items]
Borrowings under credit facility			$ 205,000,000	$ 250,000,000	$ 150,000,000
Long-term Debt, Gross			$ 673,125,000	$ 648,125,000
Restricted Stock Units (RSUs) [Member]
Subsequent Event [Line Items]
Shares granted			1,836
Restricted Stock [Member]
Subsequent Event [Line Items]
Vesting period			3 years
Shares granted			1,319
Subsequent Event [Member]
Subsequent Event [Line Items]
Long-term Debt, Gross		$ 1,100,000,000
Subsequent Event [Member] | Corporate Incentive Plan [Member]
Subsequent Event [Line Items]
Restricted stock units granted, value		16,800,000
Subsequent Event [Member] | Restricted Stock [Member]
Subsequent Event [Line Items]
Restricted stock units granted, value		$ 49,200,000
Vesting period		3 years
Executive officers [Member] | Subsequent Event [Member] | Corporate Incentive Plan [Member]
Subsequent Event [Line Items]
Restricted stock units granted, value		$ 3,300,000
Line of Credit [Member]
Subsequent Event [Line Items]
Credit facility, current maximum amount		1,000,000,000				$ 700,000,000
Line of Credit [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Borrowings under credit facility		455,000,000
Credit facility, current maximum amount		$ 1,000,000,000
Onshape [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Total purchase price allocation, net of cash acquired	$ 470,000,000