Stock-Based Incentive Compensation Plans (Summary of activity for stock appreciation rights plan) (Details) - SARs [Member]	12 Months Ended
	Dec. 31, 2019 $ / shares shares
Shares
Outstanding as of beginning of year (in shares) | shares	130,007
Granted - original (in shares) | shares	23,604
Exercised (includes shares tendered) (in shares) | shares	(39,863)
Forfeited or expired (in shares) | shares	(9,317)
Outstanding as of end of year (in shares) | shares	104,431
Vested or expected to vest as of end of year (in shares) | shares	102,944	[1]
Exercisable as of end of year (in shares) | shares	71,375
Weighted average exercise price as of beginning of year (in dollars per share) | $ / shares	$ 54.88
Weighted average exercise price granted - original (in dollars per share) | $ / shares	61.80
Weighted average exercise price exercised (includes shares tendered) (in dollars per share) | $ / shares	48.69
Weighted average exercise price forfeited or expired (in dollars per share) | $ / shares	60.75
Weighted average exercise price outstanding as of end of year (in dollars per share) | $ / shares	58.17
Weighted average exercise price vested or expected to vest as of end of year (in dollars per share) | $ / shares	58.20	[1]
Weighted average exercise price exercisable as of end of year (in dollars per share) | $ / shares	$ 55.26
Weighted average remaining contractual term outstanding as of end of year (in years)	2 years 1 month 20 days
Weighted average remaining contractual term vested or expected to vest as of end of year (in years)	2 years 1 month 13 days	[1]
Weighted average remaining contractual term exercisable as of end of year (in years)	1 year 6 months 21 days

[1] Includes estimated forfeitures.