Capital Stock (Textuals) (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Aug. 24, 2015
Equity, Class of Treasury Stock [Line Items]
Shares repurchased (less than $1 million)	$ 50	$ 25
Share Repurchase Programs
Equity, Class of Treasury Stock [Line Items]
Shares repurchased (in shares - less than 0.1 million)	0.8	0.5
Shares repurchased (less than $1 million)	$ 60	$ 39
2015 Stock Repurchase Program
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program, authorized amount			$ 500
Shares repurchased (in shares - less than 0.1 million)	0.7	0.3
Shares repurchased (less than $1 million)	$ 50	$ 25
Remaining authorized amount of repurchase	$ 288
Settlement of Employee Tax Withholding Obligations
Equity, Class of Treasury Stock [Line Items]
Shares repurchased (in shares - less than 0.1 million)	0.1	0.2
Shares repurchased (less than $1 million)	$ 10	$ 14