GOODWILL, INTANGIBLE ASSETS AND OTHER LONG-LIVED ASSETS - Goodwill Impairment, Intangible Assets and Other Long-lived Assets (Details) - USD ($) $ in Millions		3 Months Ended			9 Months Ended
		Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Finite-lived intangible assets
Cumulative impairment charges		$ 2,000			$ 2,000		$ 941
Impairment of goodwill		573		$ 0	1,062	$ 0
Goodwill	[1]	1,865			1,865		2,913
Amortization expense		41		$ 43	126	$ 132
Gross  Carrying  Amount		3,145			3,145		3,123
Accumulated Amortization		(1,307)			(1,307)		(1,169)
Net  Carrying  Amount		1,838			1,838		1,954
Supply and distribution agreements
Finite-lived intangible assets
Gross  Carrying  Amount		1,114			1,114		1,100
Accumulated Amortization		(525)			(525)		(472)
Net  Carrying  Amount		589			589		628
Technology
Finite-lived intangible assets
Gross  Carrying  Amount		172			172		170
Accumulated Amortization		(139)			(139)		(129)
Net  Carrying  Amount		33			33		41
Internet domain names
Finite-lived intangible assets
Gross  Carrying  Amount		42			42		40
Accumulated Amortization		(35)			(35)		(32)
Net  Carrying  Amount		7			7		8
Trade Names
Finite-lived intangible assets
Gross  Carrying  Amount		1,815			1,815		1,811
Accumulated Amortization		(606)			(606)		(534)
Net  Carrying  Amount		1,209			1,209		1,277
Other Intangible Assets
Finite-lived intangible assets
Gross  Carrying  Amount		2			2		2
Accumulated Amortization		(2)			(2)		(2)
Net  Carrying  Amount		0			$ 0		$ 0
Minimum | Supply and distribution agreements
Finite-lived intangible assets
Amortization Period					3 years
Minimum | Technology
Finite-lived intangible assets
Amortization Period					2 years
Minimum | Internet domain names
Finite-lived intangible assets
Amortization Period					5 years
Minimum | Trade Names
Finite-lived intangible assets
Amortization Period					4 years
Minimum | Other Intangible Assets
Finite-lived intangible assets
Amortization Period					0 years
Maximum | Supply and distribution agreements
Finite-lived intangible assets
Amortization Period					20 years
Maximum | Technology
Finite-lived intangible assets
Amortization Period					7 years
Maximum | Internet domain names
Finite-lived intangible assets
Amortization Period					20 years
Maximum | Trade Names
Finite-lived intangible assets
Amortization Period					20 years
Maximum | Other Intangible Assets
Finite-lived intangible assets
Amortization Period					15 years
OpenTable And KAYAK
Finite-lived intangible assets
Impairment of goodwill		573	$ 489		$ 1,062
Goodwill		1,000	$ 1,500		1,000
Potential decrease in fair value from 1% point decrease in profitability growth rate		100			100
Potential increase in fair value from 1% point increase in profitability growth rate		100			100
Potential decrease in fair value due to 0.5% increase in discount rate		65			65
Potential increase in fair value due to 0.5% decrease in discount rate		$ 70			$ 70

[1] (1) The balance of goodwill as of September 30, 2020 and December 31, 2019 is stated net of cumulative impairment charges of $2.0 billion and $941 million, respectively.