Summary of Changes in AOCI (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax	$ 710	$ (3,211)	$ (3,442)	$ (2,950)
Other comprehensive (loss) income, net - Foreign Currency Translation	609	280	(486)
Amounts reclassified, pretax - Foreign Currency Translation	0	2	(2)
Tax benefit (expense)	25	(43)	(4)
Other Comprehensive Income (Loss), ASU 2016-01 adoption impact on foreign currency translation Arising During Period			0
Other Comprehensive Income (Loss), ASU 2018-02 adoption impact on foreign currency translation Arising During Period		(8)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Impact of Separation of Carrier and Otis, net of Tax	3,287
Accumulated Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax	(4,483)	(6,772)	(5,718)	(4,652)
Other comprehensive (loss) income before reclassifications, net - Pension	1,842	(584)	(1,736)
Amortization of actuarial gain	373	170	344
Tax expense (benefit) reclassified - Pension	(510)	97	326
Other Comprehensive Income (Loss), ASU 2016-01 adoption impact on Defined Benefit Plan Arising During Period			0
Other Comprehensive Income (Loss), ASU 2018-02 adoption impact on Defined Benefit Plan Arising During Period		(737)
Other Comprehensive Income (Loss), Defined Benefit Plan, Impact of Separation of Carrier and Otis, net of Tax	584
AOCI, Debt Securities, Available-for-sale, Adjustment, after Tax	0	0	0	5
Other comprehensive (loss) income before reclassifications, net - AFS Securities	0	0	0
Amounts reclassified, pretax - AFS Securities	0	0	0
Tax (benefit) expense reclassified - AFS Securities	0	0	0
Other Comprehensive Income (Loss), ASU 2016-01 adoption impact on Securities Arising During Period			(5)
Other Comprehensive Income (Loss), ASU 2018-02 adoption impact on Securities Arising During Period		0
Other Comprehensive Income (Loss), Available-for-Sale Securities, Impact of Separation of Carrier and Otis, net of Tax	0
AOCI, Cash Flow Hedge, Cumulative Gain (Loss), after Tax	39	(166)	(173)	72
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification, before Tax	181	(33)	(307)
Amounts reclassified, pretax - Unrealized Hedging (Losses) Gains	82	51	(16)
Tax (benefit) expense reclassified - Unrealized Hedging (Losses) Gains	(62)	(11)	78
Other Comprehensive Income (Loss), ASU 2016-01 adoption impact on Derivatives Arising During Period			0
Other Comprehensive Income (Loss), ASU 2018-02 adoption impact on Derivatives Arising During Period		0
Other Comprehensive Income (Loss), Cash Flow Hedge, Impact of Separation of Carrier and Otis, net of Tax	4
Other comprehensive (loss) income before reclassifications, net	2,632	(337)	(2,529)
Amounts reclassified, pretax	455	223	326
Tax (benefit) expense reclassified	(547)	43	400
Reclassification from OCI, current period, ASU 2016-01 adoption impact			(5)
Reclassification from OCI, current period, ASU 2018-02 adoption impact		(745)
Other Comprehensive Income (Loss), Impact of Separation of Carrier and Otis, net of Tax	3,875
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ (3,734)	$ (10,149)	(9,333)	$ (7,525)
Accumulated Net Unrealized Gain (Loss) on Available-for-Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), ASU 2016-01 adoption impact on Securities Arising During Period			$ (5)