Equity - Accelerated Share Repurchase Program (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions						1 Months Ended	3 Months Ended	12 Months Ended
	Jul. 27, 2020	Oct. 01, 2019	Jul. 31, 2019	Jan. 02, 2019	Sep. 25, 2018	Feb. 29, 2020	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accelerated Share Repurchases [Line Items]
Total cash utilized							$ 3	$ 1,164	$ 1,240	$ 1,660
Accelerated Share Repurchases, Capped February 2020
Accelerated Share Repurchases [Line Items]
Average price paid per share (USD per share)								$ 292.13
Total cash utilized								$ 500
Accelerated Share Repurchases, Uncapped February 2020
Accelerated Share Repurchases [Line Items]
Average price paid per share (USD per share)								$ 292.13
Total cash utilized								$ 500
Authorized amount repurchased (as a percent)								85.00%
Accelerated Share Repurchases, August 2019
Accelerated Share Repurchases [Line Items]
Average price paid per share (USD per share)									$ 253.36
Total cash utilized									$ 500
Accelerated Share Repurchases, February 2019
Accelerated Share Repurchases [Line Items]
Average price paid per share (USD per share)									$ 214.65
Total cash utilized									$ 500
Authorized amount repurchased (as a percent)									85.00%
Accelerated Share Repurchases, October 2018
Accelerated Share Repurchases [Line Items]
Average price paid per share (USD per share)										$ 173.80
Total cash utilized									$ 1,240	$ 500
Authorized amount repurchased (as a percent)										85.00%
Accelerated Share Repurchases, March 2018
Accelerated Share Repurchases [Line Items]
Average price paid per share (USD per share)										$ 197.49
Total cash utilized										$ 1,000
Authorized amount repurchased (as a percent)										85.00%
Initial Award | Accelerated Share Repurchases, Capped February 2020
Accelerated Share Repurchases [Line Items]
Total number of shares purchased (shares)								1.3
Initial Award | Accelerated Share Repurchases, Uncapped February 2020
Accelerated Share Repurchases [Line Items]
Total number of shares purchased (shares)								1.4
Initial Award | Accelerated Share Repurchases, August 2019
Accelerated Share Repurchases [Line Items]
Total number of shares purchased (shares)									1.7
Initial Award | Accelerated Share Repurchases, February 2019
Accelerated Share Repurchases [Line Items]
Total number of shares purchased (shares)									2.2
Initial Award | Accelerated Share Repurchases, October 2018
Accelerated Share Repurchases [Line Items]
Total number of shares purchased (shares)										2.5
Initial Award | Accelerated Share Repurchases, March 2018
Accelerated Share Repurchases [Line Items]
Total number of shares purchased (shares)										4.5
Additional Award | Accelerated Share Repurchases, Capped February 2020
Accelerated Share Repurchases [Line Items]
Total number of shares purchased (shares)	0.2					0.2		0.4
Additional Award | Accelerated Share Repurchases, Uncapped February 2020
Accelerated Share Repurchases [Line Items]
Total number of shares purchased (shares)	0.3							0.3
Additional Award | Accelerated Share Repurchases, August 2019
Accelerated Share Repurchases [Line Items]
Total number of shares purchased (shares)		0.1				0.2			0.3
Additional Award | Accelerated Share Repurchases, February 2019
Accelerated Share Repurchases [Line Items]
Total number of shares purchased (shares)			0.1						0.1
Additional Award | Accelerated Share Repurchases, October 2018
Accelerated Share Repurchases [Line Items]
Total number of shares purchased (shares)				0.4						0.4
Additional Award | Accelerated Share Repurchases, March 2018
Accelerated Share Repurchases [Line Items]
Total number of shares purchased (shares)					0.6					0.6
Completed Award | Accelerated Share Repurchases, Capped February 2020
Accelerated Share Repurchases [Line Items]
Total number of shares purchased (shares)								1.7
Completed Award | Accelerated Share Repurchases, Uncapped February 2020
Accelerated Share Repurchases [Line Items]
Total number of shares purchased (shares)								1.7
Completed Award | Accelerated Share Repurchases, August 2019
Accelerated Share Repurchases [Line Items]
Total number of shares purchased (shares)									2.0
Completed Award | Accelerated Share Repurchases, February 2019
Accelerated Share Repurchases [Line Items]
Total number of shares purchased (shares)									2.3
Completed Award | Accelerated Share Repurchases, October 2018
Accelerated Share Repurchases [Line Items]
Total number of shares purchased (shares)										2.9
Completed Award | Accelerated Share Repurchases, March 2018
Accelerated Share Repurchases [Line Items]
Total number of shares purchased (shares)										5.1