Stock-Based Compensation Plans (Schedule Of Changes Of Restricted Stock) (Details) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
weighted average of shares for total future compensation cost related to unvested share-based awards	2 years 1 month 2 days
Restricted Stock And Restricted Stock Units [Member]
Restricted Share Units (in 000’s)
Beginning Balance (in shares) | shares	480
Ending Balance (in shares) | shares	485
Weighted Average Grant-Date Fair Value
Beginning Balance (in dollars per share) | $ / shares	$ 83.23
Ending Balance (in dollars per share) | $ / shares	$ 83.17
Share-based Payment Arrangement, Nonvested Award, Excluding Option, Cost Not yet Recognized, Amount | $	$ 23.8
weighted average period for unvested share-based RSUs to be recognized	1 year 10 months 13 days
Restricted Stock Units (RSUs) [Member]
Restricted Share Units (in 000’s)
Granted (in shares) | shares	178
Vested (in shares) | shares	(154)
Forfeited (in shares) | shares	(25)
Weighted Average Grant-Date Fair Value
Granted (in dollars per share) | $ / shares	$ 78.04
Vested (in dollars per share) | $ / shares	71.52
Forfeited (in dollars per share) | $ / shares	$ 82.96
Performance Based Restricted Share Units [Member]
Restricted Share Units (in 000’s)
Granted (in shares) | shares	75
Vested (in shares) | shares	(48)
Forfeited (in shares) | shares	(21)
Weighted Average Grant-Date Fair Value
Granted (in dollars per share) | $ / shares	$ 93.05
Vested (in dollars per share) | $ / shares	111.24
Forfeited (in dollars per share) | $ / shares	$ 97.98