BUSINESS COMBINATIONS - Reverse Recapitalization (Details) $ / shares in Units, $ in Millions		12 Months Ended
	Dec. 18, 2020 USD ($) $ / shares shares	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Common Stock
Business Combination [Line Items]
Equity issuance costs		$ 29	$ 43	$ 0
Transaction with Social Capital Hedosophia Holdings Corp. II I Common Stock
Business Combination [Line Items]
Consideration received due to reverse recapitalization	$ 377
PIPE shares issued by Social Capital Hedosophia Holdings Corp. II | shares	60,005,000
Common stock price per PIPE Shares (in usd per share) | $ / shares	$ 10.00
Total PIPE shares investment	$ 600
Exchange ratio upon Business Combination with Social Capital Hedosophia Holdings Corp. II	1.618
Opendoor Technologies Inc. Common Stock | Common Stock
Business Combination [Line Items]
Equity issuance costs	$ 44