ACQUISITIONS AND DISPOSALS - Allocation (Details) - USD ($) $ in Millions		1 Months Ended		12 Months Ended
		Dec. 31, 2021		Dec. 31, 2019	Dec. 31, 2020	[1]
Business Acquisition [Line Items]
Goodwill		$ 2,887	[1]	$ 2,913	$ 1,895
Payments to settle contingent liabilities				$ 37
Getaroom
Business Acquisition [Line Items]
Current assets	[2]	174
Identifiable intangible assets	[3]	423
Goodwill	[4]	1,020
Other noncurrent assets		10
Current liabilities		(198)
Deferred income taxes		(92)
Other noncurrent liabilities	[5]	(41)
Total consideration		1,296
Cash acquired		116
Getaroom | Travel Transaction Related Taxes
Business Acquisition [Line Items]
Other noncurrent liabilities		(38)
Getaroom | Technology
Business Acquisition [Line Items]
Identifiable intangible assets		$ 124
Weighted average useful life		4 years
Getaroom | Supply and Distribution Agreements
Business Acquisition [Line Items]
Identifiable intangible assets		$ 299
Weighted average useful life		10 years

[1] The balance of goodwill as of December 31, 2021 and 2020 is stated net of cumulative impairment charges of $2.0 billion.

[2] Includes cash and restricted cash acquired of $116 million.

[3] Acquired definite-lived intangible assets consist of supply and distribution agreements with an estimated value of $299 million and weighted-average useful life of 10 years and technology assets with an estimated value of $124 million and weighted-average useful life of 4 years.

[4] Goodwill, which is not tax deductible, reflects the synergies expected from combining the technology and expertise of Getaroom and Priceline.

[5] Includes liabilities of $38 million principally related to travel transaction taxes.