Summary of Significant Accounting Policies - Additional Information (Details) $ / shares in Units, $ in Millions			3 Months Ended	4 Months Ended	12 Months Ended
	Jun. 05, 2020 USD ($) $ / shares	Feb. 28, 2020 $ / shares shares	Mar. 31, 2020 USD ($)	Sep. 30, 2020 USD ($) $ / shares shares	Sep. 30, 2020 USD ($) $ / shares shares	Sep. 30, 2019 USD ($) shares	Sep. 30, 2018 USD ($)	Oct. 01, 2019 USD ($)	Sep. 30, 2017 USD ($)
Accounting Policies [Line Items]
Capital stock authorized (in shares) | shares		2,100,000,000
Preferred stock,, authorized (in shares) | shares		100,000,000
Preferred stock (in usd per share) | $ / shares		$ 1.00
Stockholders' equity note, stock split, conversion ratio		477,242.614671815
Advertising expense					$ 115	$ 108	$ 104
Total deficit				$ (45)	(45)	(269)	(320)		$ 308
Modification of stock-based compensation plan					769
Non-cash compensation expense					608	50	62
Operating lease liabilities				338	338
Operating lease right-of-use assets, net				273	273	0
Accrued rent						69
Accumulated deficit				(1,749)	(1,749)	(1,177)
Affiliated entity
Accounting Policies [Line Items]
Operating lease liabilities				135	$ 135
Share-based Payment Arrangement
Accounting Policies [Line Items]
Non-cash compensation expense				$ 11
Restricted Stock Units (RSUs) | Omnibus Incentive Plan
Accounting Policies [Line Items]
Shares held in employee stock option plan, allocated (in shares) | shares				28,361	28,361
IPO
Accounting Policies [Line Items]
Preferred stock, outstanding (in shares) | shares				0	0
Sale of stock (in usd per share) | $ / shares				$ 25	$ 25
Modification of stock-based compensation plan	$ 769
Accumulated Deficit
Accounting Policies [Line Items]
Total deficit				$ (1,749)	$ (1,749)	(1,177)	(1,272)		(654)
Additional Paid-in Capital
Accounting Policies [Line Items]
Total deficit				1,907	1,907	1,127	1,127		$ 1,127
Modification of stock-based compensation plan	769				769
Additional Paid-in Capital | IPO Tag-Along Right
Accounting Policies [Line Items]
Modification of stock-based compensation plan	$ 57
Cumulative Effect, Period of Adoption, Adjustment
Accounting Policies [Line Items]
Total deficit							150
Cumulative Effect, Period of Adoption, Adjustment | Accumulated Deficit
Accounting Policies [Line Items]
Total deficit							$ 139
Accounting Standards Update 2016-09
Accounting Policies [Line Items]
Decrease to share-based compensation liability			$ 38
Accounting Standards Update 2016-09 | Cumulative Effect, Period of Adoption, Adjustment
Accounting Policies [Line Items]
Total deficit						33
Accounting Standards Update 2016-09 | Cumulative Effect, Period of Adoption, Adjustment | Accumulated Deficit
Accounting Policies [Line Items]
Total deficit				$ 33	$ 33	33
Accounting Standards Update 2016-02
Accounting Policies [Line Items]
Operating lease liabilities								$ 366
Operating lease right-of-use assets, net								297
Accumulated deficit								$ 7
Accounting Standards Update 2016-02 | Cumulative Effect, Period of Adoption, Adjustment
Accounting Policies [Line Items]
Total deficit						7
Accounting Standards Update 2016-02 | Cumulative Effect, Period of Adoption, Adjustment | Accumulated Deficit
Accounting Policies [Line Items]
Total deficit						$ 7
Furniture and fixtures | Minimum
Accounting Policies [Line Items]
Property plant and equipment useful life					5 years
Furniture and fixtures | Maximum
Accounting Policies [Line Items]
Property plant and equipment useful life					7 years
Computer Equipment | Maximum
Accounting Policies [Line Items]
Property plant and equipment useful life					5 years
Machinery and equipment | Maximum
Accounting Policies [Line Items]
Property plant and equipment useful life					13 years
Building | Maximum
Accounting Policies [Line Items]
Property plant and equipment useful life					40 years
Spotify | Credit Concentration Risk | Accounts Receivable
Accounting Policies [Line Items]
Customer concentration percentage					16.00%	13.00%
Common Class A
Accounting Policies [Line Items]
Common stock authorized (in shares) | shares		1,000,000,000		1,000,000,000	1,000,000,000	1,000,000,000
Common stock outstanding (in shares) | shares				88,578,361	88,578,361	0
Common Class A | IPO
Accounting Policies [Line Items]
Common stock outstanding (in shares) | shares				88,550,000	88,550,000
Sale of stock (in usd per share) | $ / shares	$ 25
Common Class B
Accounting Policies [Line Items]
Common stock authorized (in shares) | shares		1,000,000,000		1,000,000,000	1,000,000,000	1,000,000,000
Common stock outstanding (in shares) | shares		510,000,000		421,450,000	421,450,000	505,830,022
Common Class B | IPO
Accounting Policies [Line Items]
Common stock outstanding (in shares) | shares				421,450,000	421,450,000