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Medical Claims Liability - Narrative (Details) - USD ($) $ in Millions | 3 Months Ended
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Mar. 31, 2019 | Mar. 31, 2018
Insurance [Abstract] |  |
Amounts recorded as an adjustment to premium revenues related to minimum HBR and return of premium programs | $ 8 | $ (13)
Short-duration insurance contracts, Incurred but not reported and expected development on reported claims | $ 5,569 |

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- Definition Amounts recorded as an adjustment to premium revenues related to minimum HBR and return of premium programs + References No definition available. + Details
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- References No definition available. + Details
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- Definition Undiscounted amount, after reinsurance, of incurred-but-not-reported (IBNR) liabilities plus expected development on reported claims, for claims and allocated claim adjustment expense for short-duration insurance contracts. Excludes unallocated claim adjustment expense. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 4E -URI http://asc.fasb.org/extlink&oid=99384497&loc=SL65671321-158438 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 40 -Section 50 -Paragraph 4D -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=99384497&loc=SL65671317-158438 + Details
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