Management Compensation Plans (Schedule of Summary of Changes in Stock Options Outstanding) (Details) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
As of beginning of period, number of options	823
Granted, number of options	8
Exercised, number of options	(284)
Forfeited, number of options	0
Expired, number of options	0
As of end of period, number of options	547	823
Options exercisable at end of year, number of options	415
As of beginning of period, weighted average exercise price	$ 29.93
Granted, weighted average exercise price	$ 46.87
Exercised, weighted average exercise price	$ 30.77
Forfeited, weighted average exercise price	$ 0.00
Expired, weighted average exercise price	$ 0.00
As of end of period, weighted average exercise price	$ 29.75	$ 29.93
Options exercisable at end of year, weighted average exercise price	$ 27.44
As of beginning of period, weighted average remaining contractual term	3 years 7 months 21 days	4 years 4 months 25 days
As of end of period, weighted average remaining contractual term	3 years 7 months 21 days	4 years 4 months 25 days
Options exercisable at end of year, weighted average remaining contractual term	3 years 2 months 12 days
As of beginning of period, aggregate intrinsic value	$ 12
As of end of period, aggregate intrinsic value	14	12
Options exercisable at end of year, aggregate intrinsic value	$ 12