Stockholders' Equity (Details) - USD ($) $ / shares in Units, $ in Millions					12 Months Ended
	Feb. 01, 2021	Dec. 01, 2020	Sep. 01, 2020	May 27, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 14, 2020	Jan. 25, 2013
Class of Stock [Line Items]
Preferred Stock, Shares Authorized					50,000,000	50,000,000
Preferred Stock, Shares Issued					10,062,500
Net proceeds from issuance of preferred stock in connection with public offering					$ 975	$ 0	$ 0
Payments of Dividends					$ 28	$ 0	0
Common Stock, Shares Authorized					2,000,000,000	2,000,000,000
Common Stock, Par or Stated Value Per Share					$ 0.01	$ 0.01
Net proceeds from issuance of common stock in connection with public offering					$ 975	$ 0	0
Stock Repurchase Program, Authorized Amount								$ 1,000	$ 1,000
Stock Repurchase Program, Number of Shares Authorized to be Repurchased					15,700,000
Payments for repurchase of common stock					$ 535	$ 0	$ 0
Treasury Stock, Shares					263,289,848	247,566,270
5.50% MCPS, Series A [Member]
Class of Stock [Line Items]
Preferred Stock, Shares Issued				10,062,500
Preferred Stock, Dividend Rate, Percentage				5.50%
Preferred Stock, Liquidation Preference Per Share				$ 100	$ 100
Net proceeds from issuance of preferred stock in connection with public offering				$ 975
Preferred Stock, Liquidation Preference, Value					$ 1,006
Preferred Stock, Dividends, Per Share, Cash Paid		$ 1.3750	$ 1.4361
Payments of Dividends		$ 14	$ 14
5.50% MCPS, Series A [Member] | Minimum [Member]
Class of Stock [Line Items]
Convertible Preferred Stock, Terms of Conversion					2.3834
5.50% MCPS, Series A [Member] | Maximum [Member]
Class of Stock [Line Items]
Convertible Preferred Stock, Terms of Conversion					2.9197
5.50% MCPS, Series A [Member] | Subsequent Event [Member]
Class of Stock [Line Items]
Preferred Stock, Dividends, Per Share, Cash Paid	$ 1.375
Payments of Dividends	$ 14
Dividends Payable	$ 5
Common Stock [Member]
Class of Stock [Line Items]
Stock Issued During Period, Shares, New Issues				29,382,500
Shares Issued, Price Per Share				$ 34.25
Net proceeds from issuance of common stock in connection with public offering				$ 975