Earnings Per Share (Antidilutive Securities Excluded From the Computation of Diluted Earnings Per Share) (Details) - $ / shares shares in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Weighted average shares of antidilutive security excluded from computation of diluted earnings per share (in shares)	1.2	0.7	0.4
Antidilutive stock options based on application of the treasury stock method
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Weighted average shares of antidilutive security excluded from computation of diluted earnings per share (in shares)	1.2	0.7	0.3
Weighted average exercise price of options excluded from computation of diluted earnings per share (in dollars per share)	$ 102.84	$ 108.34	$ 110.18
Antidilutive stock options due to net loss available to holders of Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Weighted average shares of antidilutive security excluded from computation of diluted earnings per share (in shares)	0.0	0.0	0.0
Antidilutive shares based on application of the treasury stock method
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Weighted average shares of antidilutive security excluded from computation of diluted earnings per share (in shares)	0.0	0.0	0.1
Antidilutive shares due to net loss available to holders of Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Weighted average shares of antidilutive security excluded from computation of diluted earnings per share (in shares)	0.0	0.0	0.0