SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2019
Significant Accounting Policies [Line Items]
Change in customer contract liability from change in estimates	$ 78,000,000
Change in customer contract liability from change in estimates, net of tax	58,000,000
Compensation costs from retirement savings plan	128,000,000	$ 224,000,000	$ 119,000,000
Advertising costs	$ 851,000,000	660,000,000	562,000,000
Normal collection period for accounts receivable	30 days
Accounts receivable reserve	$ 76,000,000	66,000,000
Goodwill impairment charge	$ 0	0	$ 0
Discount rate	3.00%
Self-insurance reserve, current	$ 166,000,000	126,000,000
Self-insurance reserve, noncurrent	323,000,000	351,000,000
Operating lease assets	888,000,000			$ 1,013,000,000
Operating lease liability	1,012,000,000			$ 1,053,000,000
Deferred revenue
Significant Accounting Policies [Line Items]
Change in customer contract liability	129,000,000
Customer contract liability	960,000,000	831,000,000
Guest loyalty program
Significant Accounting Policies [Line Items]
Change in customer contract liability	257,000,000
Customer contract liability	5,718,000,000	5,461,000,000
Revenue recognized from customer contract liability	2,211,000,000
Costs Incurred to Fulfill Contracts
Significant Accounting Policies [Line Items]
Capitalized costs	$ 351,000,000	$ 324,000,000