Benefit Plans (Stock Option and SARs Activity) (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2012
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock options and Stock appreciation rights awards outstanding at January 1	1,319,350
Weighted-average exercise price per award outstanding at January 1	$ 26.01
Number of awards granted	10,000
Weighted-average exercise price on awards granted	$ 28.32
Number of awards exercised	62,450
Weighted-average exercise price on awards exercised	$ 20.56
Number of awards forfeited, canceled or expired	108,200
Weighted-average exercise price on awards forfeited, canceled or expired	$ 30.14
Stock options and Stock appreciation rights awards outstanding at December 31	1,158,700
Weighted-average exercise price per award outstanding at December 31	$ 25.93
Aggregate intrinsic value on awards outstanding	$ 5
Weighted-average remaining contractual term on awards outstanding	4 years 11 months 24 days
Number of awards outstanding, fully vested and expected to vest	1,134,399
Weighted-average exercise price per award outstanding, fully vested and expected to vest	$ 25.93
Aggregate intrinsic value on awards outstanding, fully vested and expected to vest	5
Weighted-average remaining contractual term on awards outstanding, fully vested and expected to vest	4 years 11 months 3 days
Number of awards outstanding, exercisable	917,700
Weighted-average exercise price, awards outstanding, exercisable	$ 26.79
Aggregate intrinsic value, awards outstanding, exercisable	$ 4
Weighted-average remaining contractual term, awards outstanding, exercisable	4 years 4 months 16 days

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