Global Health Care Medical Costs Payable - Prior Year Development (Details) (Accident and health insurance [Member], USD $) In Millions, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Abstract]
(Favorable) Unfavorable incurred costs related to prior years' claims payable	$ (109)		$ (159)
Incurred costs related to prior years' claims payable percentage	0.60%		1.00%
Favorable (unfavorable) impact of prior development on shareholders' net income	25	30
Completion Factors [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Abstract]
(Favorable) Unfavorable incurred costs related to prior years' claims payable	(36)		(61)
Incurred costs related to prior years' claims payable percentage	0.20%		0.40%
Medical Cost Trend [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Abstract]
(Favorable) Unfavorable incurred costs related to prior years' claims payable	$ (73)		$ (98)
Incurred costs related to prior years' claims payable percentage	0.40%		0.60%