Stock-Based Compensation Stock Option Plans By Exercise Price Range (Details) shares in Millions	12 Months Ended
	Dec. 31, 2017 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding (in shares) | shares	10.9
Options outstanding, average remaining life	6 years 4 months
Options exercisable (in shares) | shares	5.2
Exercise Price Range $12.83 to $23.78 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price range, minimum (in dollars per share)	$ 12.83
Exercise price range, maximum (in dollars per share)	$ 23.78
Options outstanding (in shares) | shares	1.4
Options outstanding (in dollars per share)	$ 17.11
Options outstanding, average remaining life	2 years
Options exercisable (in shares) | shares	1.4
Options exercisable (in dollars per share)	$ 17.11
Exercise Price Range $23.79 to $29.75 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price range, minimum (in dollars per share)	23.79
Exercise price range, maximum (in dollars per share)	$ 29.75
Options outstanding (in shares) | shares	1.6
Options outstanding (in dollars per share)	$ 25.00
Options outstanding, average remaining life	4 years
Options exercisable (in shares) | shares	1.6
Options exercisable (in dollars per share)	$ 25.00
Exercise Price Range $29.76 to $42.17 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price range, minimum (in dollars per share)	29.76
Exercise price range, maximum (in dollars per share)	$ 42.17
Options outstanding (in shares) | shares	2.4
Options outstanding (in dollars per share)	$ 34.77
Options outstanding, average remaining life	6 years
Options exercisable (in shares) | shares	1.4
Options exercisable (in dollars per share)	$ 34.26
Exercise Price Range $42.18 to $57.25 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price range, minimum (in dollars per share)	42.18
Exercise price range, maximum (in dollars per share)	$ 57.25
Options outstanding (in shares) | shares	3.7
Options outstanding (in dollars per share)	$ 43.73
Options outstanding, average remaining life	8 years
Options exercisable (in shares) | shares	0.8
Options exercisable (in dollars per share)	$ 43.77
Exercise Price Range $57.26 to $71.85 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price range, minimum (in dollars per share)	57.26
Exercise price range, maximum (in dollars per share)	$ 71.85
Options outstanding (in shares) | shares	1.8
Options outstanding (in dollars per share)	$ 58.11
Options outstanding, average remaining life	9 years
Options exercisable (in shares) | shares	0.0
Options exercisable (in dollars per share)	$ 0.00