Segment Financial Data (Details) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) segment	Sep. 30, 2019 USD ($)
Segment Reporting Information [Line Items]
Number of operating segments \| segment			2
Revenues	$ 3,268	$ 3,313	$ 9,263	$ 9,765
Operating profit	$ 454	$ 482	$ 1,199	$ 1,378
Operating profit margin	13.90%	14.50%	12.90%	14.10%
Asset impairment charges			$ 55	$ 0
New Equipment
Segment Reporting Information [Line Items]
Revenues	$ 1,423	$ 1,450	3,840	4,221
Maintenance and Repair
Segment Reporting Information [Line Items]
Revenues	1,515	1,525	4,448	4,554
Modernization
Segment Reporting Information [Line Items]
Revenues	330	338	975	990
Service sales
Segment Reporting Information [Line Items]
Revenues	1,845	1,863	5,423	5,544
Operating Segments
Segment Reporting Information [Line Items]
Revenues	3,268	3,313	9,263	9,765
Operating profit	$ 504	$ 522	$ 1,428	$ 1,493
Operating profit margin	15.40%	15.80%	15.40%	15.30%
General corporate expenses and other
Segment Reporting Information [Line Items]
Revenues	$ 0	$ 0	$ 0	$ 0
Operating profit	$ (50)	$ (40)	$ (229)	$ (115)
Operating profit margin	0.00%	0.00%	0.00%	0.00%
Asset impairment charges			$ 67
General corporate expenses and other \| Pre-Separation Costs
Segment Reporting Information [Line Items]
Restructuring Costs			72
UNITED STATES
Segment Reporting Information [Line Items]
Revenues	$ 855	$ 899	2,550	$ 2,723
CHINA
Segment Reporting Information [Line Items]
Revenues	624	588	1,557	1,554
Other
Segment Reporting Information [Line Items]
Revenues	1,789	1,826	5,156	5,488
New Equipment \| Operating Segments
Segment Reporting Information [Line Items]
Revenues	1,423	1,450	3,840	4,221
Operating profit	$ 95	$ 115	$ 238	$ 312
Operating profit margin	6.70%	7.90%	6.20%	7.40%
Services \| Operating Segments
Segment Reporting Information [Line Items]
Revenues	$ 1,845	$ 1,863	$ 5,423	$ 5,544
Operating profit	$ 409	$ 407	$ 1,190	$ 1,181
Operating profit margin	22.20%	21.80%	21.90%	21.30%

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