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, 2017	Dec. 31, 2019	Jul. 10, 2017	Dec. 31, 2016	Jun. 30, 2015
Class of Stock [Line Items]
Common stock, Shares authorized				175,000,000		175,000,000	175,000,000
Common stock, Shares issued				106,025,000		106,025,000	80,000,000
Common stock, Shares outstanding				105,536,000		105,131,000	79,000,000
Proceeds from Issuance of Preferred Stock and Preference Stock			$ 1,866
Preferred dividends	$ 54			$ 107	$ 214
Class of stock conversion, rate		1.3333
Series A Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, Shares authorized									19,250,000
Preferred stock, Shares issued						0
Preferred stock, Shares outstanding						0
Shares Issued, Price Per Share									$ 100
Preferred Stock, Dividend Rate, Percentage				11.125%
Preferred Stock, Par or Stated Value Per Share				$ 0.01
Common Stock [Member]
Class of Stock [Line Items]
Common stock, Shares outstanding				106,025,000	79,532,000	106,025,000		79,532,000
Shares issued in stock conversion		25,529,000		25,529,000