Supplemental Condensed Consolidating Financial Information - Condensed Consolidating Balance Sheet (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 2,826	$ 3,186	$ 2,819
Investments	1,681	2,524
Restricted investments	0	169
Receivables	1,330	871
Due from (to) affiliates	0	0
Prepaid expenses and other current assets	149	239
Derivative asset	476	522
Total current assets	6,462	7,511
Property, equipment, and capitalized software, net	241	342
Goodwill and intangible assets, net	190	255	760
Restricted investments	120	119
Investments in subsidiaries	0	0
Deferred income taxes	117	103
Other assets	24	141
Total assets	7,154	8,471	7,449
Current liabilities:
Medical claims and benefits payable	1,961	2,192	$ 1,929	$ 1,685
Amounts due government agencies	967	1,542
Accounts payable and accrued liabilities	390	366
Deferred revenue	211	282
Current portion of long-term debt	241	653
Derivative liability	476	522
Total current liabilities	4,246	5,557
Long-term debt and lease financing obligations	1,217	1,516
Deferred income taxes		0
Other long-term liabilities	44	61
Total liabilities	5,507	7,134
Total stockholders' equity	1,647	1,337
Total liabilities and stockholders' equity	7,154	8,471
Parent Issuer
Current assets:
Cash and cash equivalents	70	504
Investments	100	192
Restricted investments	0	169
Receivables	2	2
Due from (to) affiliates	90	148
Prepaid expenses and other current assets	47	103
Derivative asset	476	522
Total current assets	785	1,640
Property, equipment, and capitalized software, net	176	223
Goodwill and intangible assets, net	13	15
Investments in subsidiaries	2,768	2,306
Deferred income taxes	39	17
Total assets	3,821	4,233
Current liabilities:
Medical claims and benefits payable	4	3
Accounts payable and accrued liabilities	223	178
Current portion of long-term debt	241	653
Derivative liability	476	522
Total current liabilities	944	1,356
Other long-term liabilities	13	24
Total liabilities	2,174	2,896
Total stockholders' equity	1,647	1,337
Total liabilities and stockholders' equity	3,821	4,233
Reportable Legal Entities \| Parent Issuer
Current assets:
Cash and cash equivalents	70	504
Investments	100	192
Restricted investments		169
Receivables	2	2
Due from (to) affiliates	90	148
Prepaid expenses and other current assets	47	103
Derivative asset	476	522
Total current assets	785	1,640
Property, equipment, and capitalized software, net	176	223
Goodwill and intangible assets, net	13	15
Restricted investments	0	0
Investments in subsidiaries	2,768	2,306
Deferred income taxes	39	17
Other assets	40	32
Total assets	3,821	4,233
Current liabilities:
Medical claims and benefits payable	4	3
Amounts due government agencies	0	0
Accounts payable and accrued liabilities	223	178
Deferred revenue	0	0
Current portion of long-term debt	241	653
Derivative liability	476	522
Total current liabilities	944	1,356
Long-term debt and lease financing obligations	1,217	1,516
Deferred income taxes		0
Other long-term liabilities	13	24
Total liabilities	2,174	2,896
Total stockholders' equity	1,647	1,337
Total liabilities and stockholders' equity	3,821	4,233
Reportable Legal Entities \| Other Guarantor
Current assets:
Cash and cash equivalents	2	0
Investments	0	0
Restricted investments		0
Receivables	0	0
Due from (to) affiliates	7	2
Prepaid expenses and other current assets	29	2
Derivative asset	0	0
Total current assets	38	4
Property, equipment, and capitalized software, net	0	0
Goodwill and intangible assets, net	0	0
Restricted investments	0	0
Investments in subsidiaries	(5)	75
Deferred income taxes	0	0
Other assets	0	0
Total assets	33	79
Current liabilities:
Medical claims and benefits payable	0	0
Amounts due government agencies	0	0
Accounts payable and accrued liabilities	0	1
Deferred revenue	0	0
Current portion of long-term debt	0	0
Derivative liability	0	0
Total current liabilities	0	1
Long-term debt and lease financing obligations	0	0
Deferred income taxes		0
Other long-term liabilities	0	0
Total liabilities	0	1
Total stockholders' equity	33	78
Total liabilities and stockholders' equity	33	79
Reportable Legal Entities \| Non-Guarantors
Current assets:
Cash and cash equivalents	2,754	2,682
Investments	1,581	2,332
Restricted investments		0
Receivables	1,328	869
Due from (to) affiliates	(97)	(150)
Prepaid expenses and other current assets	73	150
Derivative asset	0	0
Total current assets	5,639	5,883
Property, equipment, and capitalized software, net	65	119
Goodwill and intangible assets, net	177	240
Restricted investments	120	119
Investments in subsidiaries	0	0
Deferred income taxes	78	101
Other assets	5	110
Total assets	6,084	6,572
Current liabilities:
Medical claims and benefits payable	1,957	2,189
Amounts due government agencies	967	1,542
Accounts payable and accrued liabilities	167	188
Deferred revenue	211	282
Current portion of long-term debt	0	16
Derivative liability	0	0
Total current liabilities	3,302	4,217
Long-term debt and lease financing obligations	20	0
Deferred income taxes		15
Other long-term liabilities	32	37
Total liabilities	3,354	4,269
Total stockholders' equity	2,730	2,303
Total liabilities and stockholders' equity	6,084	6,572
Eliminations
Current assets:
Cash and cash equivalents	0	0
Investments	0	0
Restricted investments		0
Receivables	0	0
Due from (to) affiliates	0	0
Prepaid expenses and other current assets	0	(16)
Derivative asset	0	0
Total current assets	0	(16)
Property, equipment, and capitalized software, net	0	0
Goodwill and intangible assets, net	0	0
Restricted investments	0	0
Investments in subsidiaries	(2,763)	(2,381)
Deferred income taxes	0	(15)
Other assets	(21)	(1)
Total assets	(2,784)	(2,413)
Current liabilities:
Medical claims and benefits payable	0	0
Amounts due government agencies	0	0
Accounts payable and accrued liabilities	0	(1)
Deferred revenue	0	0
Current portion of long-term debt	0	(16)
Derivative liability	0	0
Total current liabilities	0	(17)
Long-term debt and lease financing obligations	(20)	0
Deferred income taxes		(15)
Other long-term liabilities	(1)	0
Total liabilities	(21)	(32)
Total stockholders' equity	(2,763)	(2,381)
Total liabilities and stockholders' equity	$ (2,784)	$ (2,413)

Medical Premium Liability Due to Agency

No definition available.

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

- Definition

Sum of the carrying values as of the balance sheet date of obligations incurred through that date and due within one year (or the operating cycle, if longer), including liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received, taxes, interest, rent and utilities, accrued salaries and bonuses, payroll taxes and fringe benefits.