Affordable Care Act, Premium Stabilization Program, Risk Adjustment, (Payable)

No definition available.

Name:	moh_AffordableCareActPremiumStabilizationProgramRiskAdjustmentPayable
Namespace Prefix:	moh_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Affordable Care Act, Premium Stabilization Program, Risk Adjustment, Receivable

+ References

No definition available.

+ Details

Name:	moh_AffordableCareActPremiumStabilizationProgramRiskAdjustmentReceivable
Namespace Prefix:	moh_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amounts Due to Government Agencies, Medical Cost Floors and Corridors

+ References

No definition available.

+ Details

Name:	moh_AmountsDuetoGovernmentAgenciesMedicalCostFloorsandCorridors
Namespace Prefix:	moh_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Investments, Maturity Period

+ References

No definition available.

+ Details

Name:	moh_InvestmentsMaturityPeriod
Namespace Prefix:	moh_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Medical Premium Liability Due to Agency

+ References

No definition available.

+ Details

Name:	moh_MedicalPremiumLiabilityDueToAgency
Namespace Prefix:	moh_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Schedule of premium revenue by health plan type.

+ References

No definition available.

+ Details

Name:	moh_ScheduleOfPremiumRevenueByHealthPlanTypeLineItems
Namespace Prefix:	moh_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount after tax of increase (decrease) to equity or (increase) decrease to net assets, resulting from the cumulative effect adjustment of a new accounting principle applied in the period of adoption.

+ References

No definition available.

+ Details

Name:	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of operating expense attributable to disposal group, including, but not limited to, discontinued operation.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 5B
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109222650&loc=SL51721673-107760

+ Details

Name:	us-gaap_DisposalGroupIncludingDiscontinuedOperationOperatingExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of cash and cash equivalents restricted as to withdrawal or usage. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(2))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=98513485&loc=SL98516268-108586

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(1)(a))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3044-108585

+ Details

Name:	us-gaap_RestrictedCashAndCashEquivalents
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	srt_ProductOrServiceAxis=moh_MedicaidExpansionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_MajorCustomersAxis=moh_CMSSubsidiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AdjustmentsForNewAccountingPronouncementsAxis=us-gaap_AccountingStandardsUpdate201409Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementEquityComponentsAxis=us-gaap_RetainedEarningsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Significant Accounting Policies - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018	Jan. 01, 2018
Schedule of Premium Revenue by Health Plan Type [Line Items]
Medical cost floors and corridors	$ 98		$ 103
Amounts due government agencies	932		967
Risk adjustment payable	568		466
Risk adjustment receivable	$ 51		34
Maturity period	10 years
Restricted cash and cash equivalents	$ 74	$ 95
Medicaid Expansion
Schedule of Premium Revenue by Health Plan Type [Line Items]
Amounts due government agencies	$ 87		$ 87
CMS Subsidies
Schedule of Premium Revenue by Health Plan Type [Line Items]
Operating expense		$ 70
ASU 2014-09
Schedule of Premium Revenue by Health Plan Type [Line Items]
Adoption of ASU				$ 6
ASU 2014-09 \| Retained Earnings
Schedule of Premium Revenue by Health Plan Type [Line Items]
Adoption of ASU				$ 7