Regulatory Capital Requirements and Restrictions on Subsidiary Cash (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Capital	$ 478,203	$ 463,601
Capital to risk weighted assets	11.48%	11.34%
Capital required for capital adequacy	$ 437,295	$ 429,077
Capital required for capital adequacy to risk weighted assets	10.50%	10.50%
Tier one risk based capital	$ 427,059	$ 428,021
Tier one risk based capital to risk weighted assets	10.25%	10.47%
Tier one risk based capital required for capital adequacy	$ 354,000	$ 347,348
Tier one risk based capital required for capital adequacy to risk weighted assets	8.50%	8.50%
Common equity tier one capital	$ 385,428	$ 386,434
Common equity tier one capital to risk weighted assets	9.25%	9.46%
Common equity tier one capital required for capital adequacy	$ 291,530	$ 286,051
Common equity tier one capital required for capital adequacy to risk weighted assets	7.00%	7.00%
Tier one leverage capital	$ 427,059	$ 428,021
Tier one leverage capital to average assets	9.39%	9.48%
Tier one leverage capital required for capital adequacy	$ 181,950	$ 180,529
Tier one leverage capital required for capital adequacy to average assets	4.00%	4.00%
Capital conservation buffer	0.0250	0.0250
Cash reserve deposit required and made	$ 0	$ 24,100
MidWestOne Bank
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Capital	$ 500,343	$ 482,106
Capital to risk weighted assets	12.03%	11.83%
Capital required for capital adequacy	$ 436,868	$ 427,877
Capital required for capital adequacy to risk weighted assets	10.50%	10.50%
Capital required to be well capitalized	$ 416,065	$ 407,502
Capital required to be well capitalized to risk weighted assets	10.00%	10.00%
Tier one risk based capital	$ 455,700	$ 453,027
Tier one risk based capital to risk weighted assets	10.95%	11.12%
Tier one risk based capital required for capital adequacy	$ 353,655	$ 346,377
Tier one risk based capital required for capital adequacy to risk weighted assets	8.50%	8.50%
Tier one risk based capital required to be well capitalized	$ 332,852	$ 326,002
Tier one risk based capital required to be well capitalized to risk weighted assets	8.00%	8.00%
Common equity tier one capital	$ 455,700	$ 453,027
Common equity tier one capital to risk weighted assets	10.95%	11.12%
Common equity tier one capital required for capital adequacy	$ 291,246	$ 285,251
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	$ 270,442	$ 264,876
Common equity tier one risk based capital required to be well capitalized to risk weighted assets	6.50%	6.50%
Tier one leverage capital	$ 455,700	$ 453,027
Tier one leverage capital to average assets	10.03%	10.06%
Tier one leverage capital required for capital adequacy	$ 181,680	$ 180,209
Tier one leverage capital required for capital adequacy to average assets	4.00%	4.00%
Tier one leverage capital required to be well capitalized	$ 227,099	$ 231,166
Tier one leverage capital required to be well capitalized to average assets	5.00%	5.00%

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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 Total risk based capital ratio (total capital divided by risk weighted assets) required to be categorized as "well capitalized", in the regulatory framework for prompt corrective action.

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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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Amount of Common Equity Tier One Risk-based Capital, as defined by regulatory framework.

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Amount of Common Equity Tier 1 Risk-based Capital required to be categorized as adequately capitalized under regulatory framework for prompt corrective action.

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Tier 1 Leverage Capital as defined in the regulations. Also called Core Capital.

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The amount of Tier 1 Leverage Capital required to be categorized as well capitalized under the regulatory framework for prompt corrective action.

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Tier 1 Leverage Capital divided by average assets as defined in the regulations.

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Tier 1 Risk Based Capital as defined in the regulations.

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Tier 1 capital divided by risk weighted assets as defined by regulations.

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