Global Health Care Medical Claims Payable (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Paid claims related to:
Add: Reinsurance and other amounts recoverable	$ 7,080us-gaap_ReinsuranceRecoverables	$ 7,299us-gaap_ReinsuranceRecoverables
Accident and health insurance [Member]
Medical Claims Payable [Abstract]
Incurred but not yet reported	1,777	1,615
Reported claims in process	288	355
Phyician incentives and other medical expense payable	115	80
Medical claims payable	2,180	2,050
Medical Claims Payable Activity [Abstract]
Claims payable, beginning balance, gross	2,050	1,856	1,305
Less: Reinsurance and other amounts recoverable	194	242	249
Balance at January 1, net	1,856	1,614	1,056
Acquired net:	0	0	504
Incurred claims related to:
Current year	16,853	16,049	14,428
Prior years	(159)	(182)	(200)
Total incurred	16,694	15,867	14,228
Paid claims related to:
Current year	14,966	14,267	12,854
Prior years	1,656	1,358	1,320
Total paid	16,622	15,625	14,174
Balance at December 31, net	1,928	1,856	1,614
Add: Reinsurance and other amounts recoverable	252	194	242
Claims payable, ending balance, gross	2,180	2,050	1,856
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Abstract]
(Favorable) Unfavorable incurred claims related to prior years' claims payable	(159)	(182)
Incurred claims related to prior years' claims payable percentage	1.00%	1.30%
Favorable (unfavorable) impact of prior development on shareholders' net income	53	77
Completion Factors [Member] \| Accident and health insurance [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Abstract]
(Favorable) Unfavorable incurred claims related to prior years' claims payable	(61)	(74)
Incurred claims related to prior years' claims payable percentage	0.40%	0.50%
Medical Cost Trend [Member] \| Accident and health insurance [Member]
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Abstract]
(Favorable) Unfavorable incurred claims related to prior years' claims payable	$ (98)	$ (108)
Incurred claims related to prior years' claims payable percentage	0.60%	0.80%

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Net medical claims payable of acquired company.

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Amount of payments made in the reporting period to settle claims incurred in prior periods and related claims settlement costs as a percentage of incurred claims as reported in the prior year.

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Liability for other medical expense payable included in medical claims payable.

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Amount of increase (decrease) in reserve for incurred claims and claim adjustment expenses attributable to insured events of prior fiscal years.

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Total amount of payments made during the reporting period to settle insured claims and pay costs incurred in the claims settlement process.

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Amount of payments made in the reporting period to settle claims incurred in the current period and related claims settlement costs.

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Amount of payments made in the reporting period to settle claims incurred in prior periods and related claims settlement costs.

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The estimated cost of settling claims under the terms of the underlying insurance policies and assumed and ceded insurance contracts as of the balance sheet date, including an estimate for claims which have been incurred but not reported and the actual and estimated costs of settling claims.

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Estimated costs as of the balance sheet date of settling insured claims and costs incurred in the claims settlement process for claims that have not yet been submitted to the insurance company for reimbursement.

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Total provision in the period for claims incurred and costs incurred in the claim settlement process.

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Amount of provision in the period for claims incurred in the reporting period and related claims settlement costs.

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Amount of provision in the period for claims incurred in prior reporting periods and related claims settlement costs.

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Liability as of the balance sheet date for amounts representing estimated cost of settling unpaid claims under the terms of the underlying insurance policies, less estimated reinsurance recoveries on such claims. This includes an estimate for claims which have been incurred but not reported. Claim adjustment expenses represent the costs estimated to be incurred in the settlement of unpaid claims.

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The accrued obligation as of the balance sheet date which represents the cost of settling insured claims and insured claims relating to insured events that have occurred but have not yet been reported to the insurer or reinsurer as of the date of the financial statements.

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Costs of settling insured claims and costs incurred in the claims settlement process for the specified year specifically for claims that have already been submitted to the insurance company for reimbursement.

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Amount after valuation allowance recoverable including premium paid under reinsurance contracts. Examples include, but are not limited to, settled and unsettled claims, incurred but not reported losses, loss adjustment expense, premium paid, policy benefits and policy reserves.

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