Stock-Based Incentive Compensation Plans (Summary of activity for stock appreciation rights plan) (Details) (Stock appreciation rights [Member], USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014
Stock appreciation rights [Member]
Summary of activity for stock options [Roll Forward]
Outstanding as of beginning of year (in shares)	354,043
Granted - original (in shares)	62,887
Exercised (includes shares tendered) (in shares)	(93,532)
Forfeited or expired (in shares)	(15,439)
Outstanding as of end of year (in shares)	307,959
Vested or expected to vest as of end of year (in shares)	292,889	[1]
Exercisable as of end of year (in shares)	171,114
Summary of activity for stock options, additional disclosures [Abstract]
Weighted average exercise price as of beginning of year (in dollars per share)	$ 29.00
Weighted average exercise price granted - original (in dollars per share)	$ 50.41
Weighted average exercise price exercised (includes shares tendered) (in dollars per share)	$ 24.86
Weighted average exercise price forfeited or expired (in dollars per share)	$ 35.82
Weighted average exercise price outstanding as of end of year (in dollars per share)	$ 34.28
Weighted average exercise price vested or expected to vest as of end of year (in dollars per share)	$ 34.20	[1]
Weighted average exercise price exercisable as of end of year (in dollars per share)	$ 31.28
Weighted average remaining contractual term outstanding as of end of year (in years)	2 years 6 months 11 days
Weighted average remaining contractual term vested or expected to vest as of end of year (in years)	2 years 6 months	[1]
Weighted average remaining contractual term exercisable as of end of year (in years)	1 year 10 months 21 days
Aggregate intrinsic value outstanding as of end of year	$ 7
Aggregate intrinsic value vested or expected to vest as of end of year	7	[1]
Aggregate intrinsic value exercisable as of end of year	$ 5

[1] Includes estimated forfeitures.