Capital Stock (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions				12 Months Ended
	Jul. 02, 2018	Jun. 29, 2018	Jun. 24, 2015	Dec. 31, 2018	Dec. 31, 2020	Dec. 31, 2019	Jun. 30, 2015
Class of Stock [Line Items]
Common stock, Shares authorized					175,000,000	175,000,000
Common stock, Shares issued					106,025,000	106,025,000
Common stock, Shares outstanding					104,793,000	105,131,000
Class of stock conversion, rate		1.3333
Preferred dividends	$ 54			$ 107
Proceeds from Issuance of Preferred Stock and Preference Stock			$ 1,866
Series A Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, Shares issued					0	0
Preferred stock, Shares outstanding					0	0
Preferred Stock, Dividend Rate, Percentage				11.125%
Preferred Stock, Par or Stated Value Per Share				$ 0.01
Preferred stock, Shares authorized							19,250,000
Shares Issued, Price Per Share							$ 100
Common Stock [Member]
Class of Stock [Line Items]
Shares issued in stock conversion		25,529,000		25,529,000