Accumulated Other Comprehensive Loss - Reclassifications (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Reclassifications out of accumulated other comprehensive income loss by component
Interest expense	$ 352	$ 389
Income tax expense	(202)	(157)
Other income, net	70	34
Total before tax	801	632
Net of tax	599	475
Decrease (Increase) in Net Income | Interest rate swaps
Reclassifications out of accumulated other comprehensive income loss by component
Interest expense	22	20
Income tax expense	(5)	(5)
Net of tax	17	15
Decrease (Increase) in Net Income | Net actuarial loss
Reclassifications out of accumulated other comprehensive income loss by component
Other income, net	37	50
Decrease (Increase) in Net Income | Prior service cost
Reclassifications out of accumulated other comprehensive income loss by component
Other income, net	(1)	2
Decrease (Increase) in Net Income | Defined benefit plan
Reclassifications out of accumulated other comprehensive income loss by component
Income tax expense	(9)	(13)
Total before tax	36	52
Net of tax	$ 27	$ 39