Postretirement Benefits (Details 7) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Amounts included in shareholders' equity (unamortized):
Net actuarial loss	$ 95	$ 220
Prior service cost	6	6
Net amount not yet recognized	101	226
Amounts that will be amortized from accumulated other comprehensive income into pension cost during next fiscal year
Estimated net actuarial loss that will be amortized from accumulated other comprehensive income into pension cost during next fiscal year, before tax	6
Estimated net prior service cost that will be amortized from accumulated other comprehensive income into pension cost during next fiscal year, before tax	$ 1