Net Income Per Share (Narrative) (Details) - USD ($) shares in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 13, 2018	Feb. 28, 2018
Terminated stock repurchase program
Equity, Class of Treasury Stock [Line Items]
Terminated stock repurchase program						$ 100,000,000
Common stock repurchase program
Equity, Class of Treasury Stock [Line Items]
Authorized amount					$ 2,000,000,000
Purchases of treasury stock (shares)	200	5	400	22
Remaining authorized amount	$ 1,500,000,000		$ 1,500,000,000