Share Repurchase Program (Details) - USD ($) $ / shares in Units, $ in Millions		1 Months Ended		3 Months Ended										9 Months Ended		10 Months Ended	177 Months Ended
		Oct. 20, 2021	Jun. 30, 2021	Sep. 30, 2021		Jun. 30, 2021		Mar. 31, 2021	[3]	Sep. 30, 2020		Mar. 31, 2020		Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Sep. 30, 2021	Apr. 01, 2019
Shares Repurchased [Line Items]
BOD authorized																		150,000,000
Stock repurchase program expiration date														Mar. 31, 2022
Aggregate cost				$ 1,409										$ 5,926	$ 2,956		$ 46,800
Shares repurchased				8,604,239	[1]	12,204,409	[2]	6,691,421		4,045,575	[1]	14,305,793	[3]	27,500,069	18,351,368
Average purchase price	[4]			$ 210.31	[1]	$ 222.46	[2]	$ 209.50		$ 98.87	[1]	$ 178.66	[3]	$ 215.51	$ 161.07
Remaining number of shares that may be repurchased under current authority				83,522,901										83,522,901			83,522,901
Treasury stock, value				$ 46,372										$ 46,372		$ 40,420	$ 46,372
Accelerated Share Repurchase Agreement [Member]
Shares Repurchased [Line Items]
Aggregate cost			$ 2,000													$ 2,000
Shares repurchased			7,209,156	1,983,859		7,209,156				4,045,575		8,786,380				8,786,380
Average purchase price														$ 217.56	$ 155.86
Subsequent Event [Member]
Shares Repurchased [Line Items]
Aggregate cost		$ 405
Shares repurchased		1,900,000

[1] Includes an incremental 1,983,859 and 4,045,575 shares received upon final settlement in September 2021 and July 2020, respectively, under accelerated share repurchase programs.

[2] Includes 7,209,156 shares repurchased in May 2021 under accelerated share repurchase programs.

[3] Includes 8,786,380 shares repurchased in February 2020 under accelerated share repurchase programs.

[4] In the period of the final settlement, the average price paid under the accelerated share repurchase programs is calculated based on the total program value less the value assigned to the initial delivery of shares. The average price of the completed 2021 and 2020 accelerated share repurchase programs was $217.56 and $155.86, respectively.