Global Health Care Medical Costs Payable - Prior Year Development (Details) - Accident and health insurance [Member] - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2015	Jun. 30, 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	$ (182)		$ (159)
Incurred costs related to prior years' claims payable percentage	1.10%		1.00%
Favorable (unfavorable) impact of prior development on shareholders' net income	$ 44	$ 46
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	$ (49)		$ (61)
Incurred costs related to prior years' claims payable percentage	0.30%		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	$ (100)		$ (98)
Incurred costs related to prior years' claims payable percentage	0.60%		0.60%
Reinsurance Reimbursements Under Health Care Reform [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	$ (33)
Incurred costs related to prior years' claims payable percentage	0.20%