Retirement Benefits and Share-based Compensation - Share-based Compensation (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period for stock options	10 years
Period for graded vesting methodology	3 years
Allocated share-based compensation expense	$ 1	$ 2	$ 2
Employee stock compensation expense, allocation percentage	3.00%
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense	$ 6	$ 5	$ 6
Employee stock compensation expense, allocation percentage	5.00%
Performance Based Restricted Stock Unit [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSU performance period	1 year
RSU restriction period	2 years
Time-Based Restricted Stock Unit [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSU vesting percentage after first anniversary	33.33%
RSU vesting percentage after second anniversary	33.33%
RSU vesting percentage after third anniversary	33.34%