Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Increase (Decrease) Accumulated Other Comprehensive Loss, Net of Tax
Other comprehensive income (loss)	$ (117)	$ (86)	$ (592)	$ (17)
Net Effect of Exchange Rate Fluctuations
Increase (Decrease) Accumulated Other Comprehensive Loss, Net of Tax
Balance at beginning of the period	(1,321)	(830)	(813)	(889)
Change before reclassifications	1	(96)	(507)	(37)
Other comprehensive income (loss)	(148)	(96)	(656)	(37)
Balance at end of the period	(1,469)	(926)	(1,469)	(926)
Change in Certain Derivative Instruments
Increase (Decrease) Accumulated Other Comprehensive Loss, Net of Tax
Balance at beginning of the period	(21)	(22)	(14)	(18)
Change before reclassifications	(88)	(50)	(81)	(46)
Amounts reclassified from accumulated other comprehensive income (loss)	78	52	67	38
Translation effect	(1)	2	(3)	5
Tax effect	(1)	1	(2)	4
Other comprehensive income (loss)	(11)	5	(18)	1
Balance at end of the period	(32)	(17)	(32)	(17)
Employee Benefit Plans
Increase (Decrease) Accumulated Other Comprehensive Loss, Net of Tax
Balance at beginning of the period	(966)	(1,039)	(1,016)	(1,061)
Change before reclassifications	30	8	35	6
Amounts reclassified from accumulated other comprehensive income (loss)	17	12	51	37
Translation effect	(9)	7	4	6
Tax effect			(2)
Other comprehensive income (loss)	42	27	92	49
Balance at end of the period	(924)	(1,012)	(924)	(1,012)
Accumulated Other Comprehensive Loss.
Increase (Decrease) Accumulated Other Comprehensive Loss, Net of Tax
Balance at beginning of the period	(2,308)	(1,891)	(1,843)	(1,968)
Change before reclassifications	(57)	(138)	(553)	(77)
Amounts reclassified from accumulated other comprehensive income (loss)	95	64	118	75
Translation effect	(10)	9	1	11
Tax effect	(1)	1	(4)	4
Other comprehensive income (loss)	(117)	(64)	(582)	13
Balance at end of the period	(2,425)	$ (1,955)	(2,425)	$ (1,955)
Australia And New Zealand ("ANZ") business | Net Effect of Exchange Rate Fluctuations
Increase (Decrease) Accumulated Other Comprehensive Loss, Net of Tax
Amounts reclassified from accumulated other comprehensive income (loss)	(149)		(149)
Australia And New Zealand ("ANZ") business | Change in Certain Derivative Instruments
Increase (Decrease) Accumulated Other Comprehensive Loss, Net of Tax
Amounts reclassified from accumulated other comprehensive income (loss)	1		1
Australia And New Zealand ("ANZ") business | Employee Benefit Plans
Increase (Decrease) Accumulated Other Comprehensive Loss, Net of Tax
Amounts reclassified from accumulated other comprehensive income (loss)	4		4
Australia And New Zealand ("ANZ") business | Accumulated Other Comprehensive Loss.
Increase (Decrease) Accumulated Other Comprehensive Loss, Net of Tax
Amounts reclassified from accumulated other comprehensive income (loss)	$ (144)		$ (144)