This represents the recorded investment for impaired mortgage loans held-for-investment.

No definition available.

Name:	micc_RecordedInvestmentForImpairedMortgageLoansHeldForInvestment
Namespace Prefix:	micc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The reserve to cover probable credit losses related to specifically identified fixed maturity real estate loans as well as probable credit losses inherent in the remainder of that loan portfolio.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 60

-Paragraph 47

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 310

-Section 45

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=6873192&loc=d3e21338-158488

+ Details

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

- Definition

Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 15

-Subparagraph (c)(1)

-URI http://asc.fasb.org/extlink&oid=7512638&loc=d3e5212-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 17

-URI http://asc.fasb.org/extlink&oid=7512638&loc=d3e5258-111524

+ Details

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

- Definition

Amount of interest income recognized that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were impaired.

+ References

+ Details

Name:	us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 14A

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=7512638&loc=SL6953550-111524

+ Details

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

- Definition

Amount of unpaid principal balance of impaired financing receivables with related allowance for credit losses and without related allowance for credit losses.

+ References

+ Details

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

- Details

Name:	us-gaap_LoanAndLeaseReceivablesImpairedAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Investments (Impaired Mortgage Loans) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012	Dec. 31, 2011
Impaired Mortgage Loans
Unpaid principal balance	$ 80		$ 80			$ 76
Valuation allowances	34	42	34	42	35	35	57	61
Recorded investment	69		69			65
Average Investment	74	23	74	28
Interest Income	1	0	2	1
Loans with a Valuation Allowance [Member]
Impaired Mortgage Loans
Unpaid principal balance	27		27			76
Recorded investment	26		26			76
Valuation allowances	7		7			11
Recorded investment	19		19			65
Loans Without Valuation Allowances [Member]
Impaired Mortgage Loans
Unpaid principal balance	53		53			0
Recorded investment	50		50			0
Commercial mortgage loans portfolio segment [Member]
Impaired Mortgage Loans
Unpaid principal balance	75		75			76
Valuation allowances	30	39	30	39	32	32	54	58
Recorded investment	65		65			65
Average Investment	72	23	73	28
Interest Income	1	0	2	1
Commercial mortgage loans portfolio segment [Member] \| Loans with a Valuation Allowance [Member]
Impaired Mortgage Loans
Unpaid principal balance	22		22			76
Recorded investment	22		22			76
Valuation allowances	7		7			11
Recorded investment	15		15			65
Commercial mortgage loans portfolio segment [Member] \| Loans Without Valuation Allowances [Member]
Impaired Mortgage Loans
Unpaid principal balance	53		53			0
Recorded investment	50		50			0
Agricultural [Member]
Impaired Mortgage Loans
Unpaid principal balance	5		5			0
Valuation allowances	4	3	4	3	3	3	3	3
Recorded investment	4		4			0
Average Investment	2	0	1	0
Interest Income	0	0	0	0
Agricultural [Member] \| Loans with a Valuation Allowance [Member]
Impaired Mortgage Loans
Unpaid principal balance	5		5			0
Recorded investment	4		4			0
Valuation allowances	0		0			0
Recorded investment	4		4			0
Agricultural [Member] \| Loans Without Valuation Allowances [Member]
Impaired Mortgage Loans
Unpaid principal balance	0		0			0
Recorded investment	$ 0		$ 0			$ 0