Share Repurchase Program (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended			2 Months Ended		3 Months Ended												12 Months Ended			156 Months Ended
	Feb. 06, 2020	Mar. 31, 2019	Jun. 30, 2018	Sep. 30, 2019	Dec. 31, 2018	Dec. 31, 2019	Sep. 30, 2019		Jun. 30, 2019	Mar. 31, 2019		Dec. 31, 2018		Sep. 30, 2018	Jun. 30, 2018		Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2019	Apr. 01, 2019
Share Repurchase Program [Line Items]
BOD authorized																						150,000,000
Stock repurchase program expiration date																		Mar. 31, 2022
Aggregate cost																		$ 5,804	$ 8,225	$ 4,013	$ 37,200
Shares repurchased						3,582,212	9,529,733	[1]	3,732,974	18,149,450	[2]	12,490,632	[3]	2,239,405	33,229,992	[4]	9,259,004	34,994,369	57,219,033
Average purchase price						$ 167.32	$ 163.30	[1]	$ 171.24	$ 165.79	[2]	$ 153.04	[3]	$ 151.94	$ 142.74	[4]	$ 132.84	$ 165.85	$ 143.75
Remaining number of shares that may be repurchased under current authority						133,155,081												133,155,081			133,155,081
Accelerated Share Repurchase Agreement [Member]
Share Repurchase Program [Line Items]
Aggregate cost		$ 2,500	$ 3,600
Shares repurchased		11,795,930	19,870,292	3,172,900	4,457,356		3,172,900			11,795,930		4,457,356			19,870,292
Subsequent Event [Member]
Share Repurchase Program [Line Items]
Aggregate cost	$ 493
Shares repurchased	2,700,000

[1] Includes 3,172,900 shares repurchased in August 2019 under accelerated share repurchase programs.

[2] Includes 11,795,930 shares repurchased in February 2019 under accelerated share repurchase programs.

[3] Includes 4,457,356 shares repurchased in October 2018 under accelerated share repurchase programs.

[4] Includes 19,870,292 shares repurchased in June 2018 under accelerated share repurchase programs.