XML 65 R55.htm IDEA: XBRL DOCUMENT v3.25.3

Note 5 - Deposits (Details Textual) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2025	Dec. 31, 2024
Deposits	$ 4,811,813	$ 4,698,366
Increase (Decrease) in Deposits	$ 113,000
Aggregate Increase (Decrease) in Percentage of Deposits	2.40%

X

- Definition

The percentage of increase or (decrease) during the period in deposit liabilities.

+ References

No definition available.

+ Details

Name:	mbwm_AggregateIncreaseDecreaseInPercentageOfDeposits
Namespace Prefix:	mbwm_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

X

- Definition

The aggregate of all deposit liabilities held by the entity, including foreign and domestic, interest and noninterest bearing; may include demand deposits, saving deposits, Negotiable Order of Withdrawal (NOW) and time deposits among others.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(12))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1

+ Details

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

X

- Definition

The net cash inflow or outflow for the increase (decrease) in the beginning and end of period deposits balances.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 942
-SubTopic 230
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479024/942-230-45-1

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 8
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-8

+ Details

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