v3.8.0.1

Medical Claims Liability - Cumulative incurred and Paid Claims (Details) - Health insurance product line - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Claims Development [Line Items]
Short-duration insurance contracts, incurred claims and allocated claim adjustment expense, net	$ 102,831
Short-duration insurance contracts, cumulative paid claims and allocated claim adjustment expense, net	98,563
Short-duration insurance contracts, liability for unpaid claims and allocated claim adjustment expense, net, not separately presented	4,268
Short-duration insurance contracts, accident year 2015
Claims Development [Line Items]
Short-duration insurance contracts, incurred claims and allocated claim adjustment expense, net	30,310	$ 30,325	$ 30,619
Short-duration insurance contracts, cumulative paid claims and allocated claim adjustment expense, net	30,297	30,031	$ 27,664
Short-duration insurance contracts, accident year 2016
Claims Development [Line Items]
Short-duration insurance contracts, incurred claims and allocated claim adjustment expense, net	34,296	34,655
Short-duration insurance contracts, cumulative paid claims and allocated claim adjustment expense, net	34,070	$ 31,043
Short-duration insurance contracts, accident year 2017
Claims Development [Line Items]
Short-duration insurance contracts, incurred claims and allocated claim adjustment expense, net	38,225
Short-duration insurance contracts, cumulative paid claims and allocated claim adjustment expense, net	$ 34,196

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- Definition

Amount, after reinsurance, of paid claims and allocated claim adjustment expense used in claims development for short-duration insurance contracts. Excludes unallocated claim adjustment expense.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 40
-Section 50
-Paragraph 4B
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=65670685&loc=SL65671311-158438

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- Definition

Undiscounted amount, after reinsurance, of incurred claims and allocated claim adjustment expense used in claims development for short-duration insurance contracts. Excludes unallocated claim adjustment expense.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 40
-Section 50
-Paragraph 4B
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=65670685&loc=SL65671311-158438

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- Definition

Undiscounted amount, after reinsurance, of the liability for unpaid claims and allocated claim adjustment expense for short-duration insurance contracts for accident years not separately presented in claim development information. Excludes unallocated claim adjustment expense.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 40
-Section 50
-Paragraph 4B
-URI http://asc.fasb.org/extlink&oid=65670685&loc=SL65671311-158438

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