Summary of Significant Accounting Policies (Narrative) (Details) - USD ($)	1 Months Ended			3 Months Ended	12 Months Ended
	Feb. 28, 2022	Jan. 31, 2022	Dec. 31, 2020	Dec. 31, 2020	Sep. 30, 2022	Dec. 31, 2021	Sep. 30, 2021	Sep. 30, 2020
Summary Of Significant Accounting Policies [Line Items]
Percent of standalone selling price for subscriptions that contains software license					55.00%
Percent of standalone selling price for subscriptions that contains support					45.00%
Contract with customer, total liability					$ 34,200,000		$ 40,300,000
Proceeds from sales of short- and long-term marketable securities			$ 56,200,000	$ 56,200,000	0		56,170,000	$ 1,521,000
Allowance for doubtful accounts receivable					400,000		300,000	500,000
Allowance for credit loss, writeoff					400,000		100,000	200,000
Bad debt expense (recoveries) including general and administrative expense, net					500,000		200,000	0.0
Lease expiration date						2037
Development costs for software					0		0	0
Advertising expense					8,600,000		7,100,000	3,800,000
Cumulative translation adjustment gains (loss)					160,200,000		(67,500,000)
Pension benefits, before tax					5,400,000		(30,200,000)
Accumulated other comprehensive (income) loss, defined benefit plan, after tax					3,900,000		21,500,000
Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Net Investment Hedges, Before Tax					16,900,000		6,500,000
Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Net Investment Hedges, Effect Net of Tax					$ 10,600,000		$ 6,500,000
Share price per share					$ 0.01		$ 0.01
Net income (loss)					$ (313,081,000)		$ (476,923,000)	$ (130,695,000)
Impairment charges					0		0
Non-marketable equity investments					1,000,000.0		2,200,000
Purchased Software
Summary Of Significant Accounting Policies [Line Items]
Finite-lived intangible assets acquired					6,000,000.0		600,000
Matterport, Inc.
Summary Of Significant Accounting Policies [Line Items]
Cost method investments							8,700,000
Original investment							8,700,000
Aggregate realized gain					34,000,000.0
Fair value of shares							77,500,000
Unrealized gain on value of shares							68,800,000
Matterport, Inc. | Equity Securities [Member]
Summary Of Significant Accounting Policies [Line Items]
Cost method investments					8,700,000
Value of remaining shares held for sale	$ 3,600,000	$ 39,100,000
Share price per share	$ 7.6	$ 9.1
Net income (loss)					(34,800,000)
Original investment					$ 8,700,000
Minimum
Summary Of Significant Accounting Policies [Line Items]
Percent of standalone selling price for subscriptions					5.00%
Minimum | Computer Hardware And Software
Summary Of Significant Accounting Policies [Line Items]
Amortization period (in years)					3 years
Minimum | Furniture And Fixtures
Summary Of Significant Accounting Policies [Line Items]
Amortization period (in years)					3 years
Maximum
Summary Of Significant Accounting Policies [Line Items]
Percent of standalone selling price for subscriptions					50.00%
Maximum | Purchased Software
Summary Of Significant Accounting Policies [Line Items]
Amortization period (in years)					16 years
Maximum | Customer Lists
Summary Of Significant Accounting Policies [Line Items]
Amortization period (in years)					13 years
Maximum | Trademarks
Summary Of Significant Accounting Policies [Line Items]
Amortization period (in years)					12 years
Maximum | Computer Hardware And Software
Summary Of Significant Accounting Policies [Line Items]
Amortization period (in years)					5 years
Maximum | Furniture And Fixtures
Summary Of Significant Accounting Policies [Line Items]
Amortization period (in years)					12 years
ASU 2018-15 | Other Assets
Summary Of Significant Accounting Policies [Line Items]
Capitalized costs					$ 14,300,000		$ 2,800,000
Not Designated as Hedging Instrument | Foreign Exchange Forward
Summary Of Significant Accounting Policies [Line Items]
Derivative maturity					4 months
Net Investment Hedging | Designated as Hedging Instrument | Foreign Exchange Forward
Summary Of Significant Accounting Policies [Line Items]
Derivative maturity					3 months