Regulatory Capital Requirements and Restrictions on Subsidiary Cash (Details)	Jul. 28, 2020 USD ($)	Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Cash reserve deposit required and made		$ 0	$ 0
Capital		$ 589,205,000	$ 572,437,000
Capital to risk weighted assets		0.1375	0.1341
Capital required for capital adequacy		$ 450,010,000	$ 448,068,000
Capital required for capital adequacy to risk weighted assets		0.1050	0.1050
Tier one risk based capital		$ 477,086,000	$ 456,526,000
Tier one risk based capital to risk weighted assets		0.1113	0.1070
Tier one risk based capital required for capital adequacy		$ 364,294,000	$ 362,722,000
Tier one risk based capital required for capital adequacy to risk weighted assets		0.0850	0.0850
Common equity tier one capital		$ 435,279,000	$ 414,763,000
Common equity tier one capital to risk weighted assets		10.16%	9.72%
Common equity tier one capital required for capital adequacy		$ 300,006,000	$ 298,712,000
Common equity tier one capital required for capital adequacy to risk weighted assets		7.00%	7.00%
Tier one leverage capital		$ 477,086,000	$ 456,526,000
Tier one leverage capital to average assets		0.0878	0.0850
Tier one leverage capital required for capital adequacy		$ 217,315,000	$ 214,795,000
Tier one leverage capital required for capital adequacy to average assets		0.0400	0.0400
Capital conservation buffer		0.0250	0.0250
Subordinated debt
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Interest rate		6.50%
5.75% Fixed to floating subordinated notes \| Subordinated debt
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Interest rate	5.75%
5.75% Fixed to floating subordinated notes \| Subordinated debt \| Private placement
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Sale of equity	$ 65,000,000.0
MidWestOne Bank
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Capital		$ 563,501,000	$ 547,558,000
Capital to risk weighted assets		0.1319	0.1289
Capital required for capital adequacy		$ 448,555,000	$ 446,113,000
Capital required for capital adequacy to risk weighted assets		0.1050	0.1050
Capital required to be well capitalized		$ 427,195,000	$ 424,870,000
Capital required to be well capitalized to risk weighted assets		0.1000	0.1000
Tier one risk based capital		$ 520,716,000	$ 500,981,000
Tier one risk based capital to risk weighted assets		0.1219	0.1179
Tier one risk based capital required for capital adequacy		$ 363,116,000	$ 361,139,000
Tier one risk based capital required for capital adequacy to risk weighted assets		0.0850	0.0850
Tier one risk based capital required to be well capitalized		$ 341,756,000	$ 339,896,000
Tier one risk based capital required to be well capitalized to risk weighted assets		0.0800	0.0800
Common equity tier one capital		$ 520,716,000	$ 500,981,000
Common equity tier one capital to risk weighted assets		12.19%	11.79%
Common equity tier one capital required for capital adequacy		$ 299,037,000	$ 297,409,000
Common equity tier one capital required for capital adequacy to risk weighted assets		7.00%	7.00%
Common equity tier one risk based capital required to be well capitalized		$ 277,677,000	$ 276,165,000
Common equity tier one risk based capital required to be well capitalized to risk weighted assets		6.50%	6.50%
Tier one leverage capital		$ 520,716,000	$ 500,981,000
Tier one leverage capital to average assets		0.0960	0.0935
Tier one leverage capital required for capital adequacy		$ 216,913,000	$ 214,251,000
Tier one leverage capital required for capital adequacy to average assets		0.0400	0.0400
Tier one leverage capital required to be well capitalized		$ 271,142,000	$ 271,992,000
Tier one leverage capital required to be well capitalized to average assets		0.0500	0.0500

Ratio of Common equity Tier 1 required for capital adequacy purposes as defined in the regulations.

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Common equity Tier 1 actual ratio as defined in the regulations.

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The ratio Tier 1 Leverage Capital required to be categorized as well capitalized as defined in the regulatory framework for prompt corrective action.

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Leverage buffer percentage as defined by regulatory framework.

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Amount of total capital as defined by regulatory framework.

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Amount of minimum total risk-based capital required for capital adequacy as defined by regulatory framework.

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Cash deposited in a special reserve account for the exclusive benefit of customers pursuant to SEC Regulations.

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Contractual interest rate for funds borrowed, under the debt agreement.

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