Business Acquisitions Business Acquisition (Assets Liabilities Acquired) (Details) individual_member in Millions, $ in Millions	3 Months Ended
Mar. 31, 2020 USD ($) individual_member states	Dec. 31, 2019 USD ($)
Business Acquisition [Line Items]
Goodwill	$ 21,661	$ 20,500
Number of States in which Company Operates \| states	50
Beacon Health Options [Member]
Business Acquisition [Line Items]
Number Of Lives Served \| individual_member	34
Number of States in which Company Operates \| states	50
Beacon Health Options [Member] \| Government Business Segment [Member]
Business Acquisition [Line Items]
Goodwill	$ 1,049
Other intangible assets	$ 752
Minimum [Member] \| Beacon Health Options [Member] \| Government Business Segment [Member] \| Customer relationships and provider networks
Business Acquisition [Line Items]
Intangible assets amortization period, years	9 years
Maximum [Member] \| Beacon Health Options [Member] \| Government Business Segment [Member] \| Customer relationships and provider networks
Business Acquisition [Line Items]
Intangible assets amortization period, years	21 years

Number Of Lives Served

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- Definition

Weighted average amortization period of finite-lived intangible assets acquired either individually or as part of a group of assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16265-109275

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Amount of intangible assets, excluding goodwill, acquired at the acquisition date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=116869197&loc=d3e4845-128472

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- Definition

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=77989000&loc=SL49117168-202975

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=99380562&loc=d3e13770-109266

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- Definition

The number of states the entity operates in as of the balance sheet date.

+ References

No definition available.

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