Segment Reporting - Condensed Balance Sheet - By Segment (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Assets	$ 25,966	$ 25,436
Liabilities	22,799	22,139
Corporate and Other [Member]
Segment Reporting Information [Line Items]
Assets	6,342	7,458
Liabilities	11,720	11,780
Intersegment Elimination
Segment Reporting Information [Line Items]
Assets	(2,999)	(3,032)
Liabilities	141	108
Las Vegas, NV [Member] | Operating Segments
Segment Reporting Information [Line Items]
Assets	13,990	14,145
Liabilities	5,856	5,239
Other U.S. | Operating Segments
Segment Reporting Information [Line Items]
Assets	8,633	6,865
Liabilities	$ 5,082	$ 5,012