Amounts for the payment of Federal Home Loan Bank loans.

No definition available.

Name:	fhlbdm_PaymentsForFederalHomeLoanBankLoans
Namespace Prefix:	fhlbdm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Proceeds from Federal Home Loan Bank Loans

+ References

No definition available.

+ Details

Name:	fhlbdm_ProceedsfromFederalHomeLoanBankLoans
Namespace Prefix:	fhlbdm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Schedule of Other Transactions [Line Items]

+ References

No definition available.

+ Details

Name:	fhlbdm_ScheduleOfOtherTransactionsLineItems
Namespace Prefix:	fhlbdm_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of Federal Home Loan Bank (FHLBank) loans from another FHLBank.

+ References

No definition available.

+ Details

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

- Definition

Amount of Federal Home Loan Bank (FHLBank) loans to another FHLBank.

+ References

No definition available.

+ Details

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

- Definition

Amount of cash outflow for disbursement to borrower related to advance, made by Federal Home Loan Bank (FHLBank), classified as investing activity.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3213-108585

+ Details

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

- Definition

Amount of cash inflow from Federal Home Loan Bank (FHLBank) borrowing, classified as financing activity.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3255-108585

+ Details

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

- Definition

Amount of cash outflow for repayment of Federal Home Loan Bank (FHLBank) borrowing, classified as financing activity.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3291-108585

+ Details

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

- Details

Name:	srt_FederalHomeLoanBankAdvancesBranchOfFHLBBankAxis=srt_FederalHomeLoanBankOfAtlantaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_FederalHomeLoanBankAdvancesBranchOfFHLBBankAxis=srt_FederalHomeLoanBankOfBostonMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Activities with Other FHLBanks (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Schedule of Other Transactions [Line Items]
Payments for FHLBank Advance, Investing Activities	$ 78,332	$ 60,649
Federal Home Loan Bank of Atlanta [Member]
Schedule of Other Transactions [Line Items]
Loans from Other Federal Home Loan Banks		0		$ 500
Payments for Federal Home Loan Bank Advances		565
Proceeds from Federal Home Loan Bank Loans		(565)
Loans to Other Federal Home Loan Banks		0		$ 0
Proceeds from FHLBank Borrowings, Financing Activities		0
Payments of FHLBank Borrowings, Financing Activities		$ (500)
Federal Home Loan Bank of Boston [Member]
Schedule of Other Transactions [Line Items]
Payments for Federal Home Loan Bank Advances	250
Proceeds from Federal Home Loan Bank Loans	(250)
Loans to Other Federal Home Loan Banks	$ 0		$ 0