Regulatory Capital Requirements and Restrictions on Subsidiary Cash (Details) $ in Thousands	Jun. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Capital	$ 485,309	$ 463,601
Capital to risk weighted assets	0.1172	0.1134
Capital required for capital adequacy	$ 434,970	$ 429,077
Capital required for capital adequacy to risk weighted assets	0.1050	0.1050
Tier one risk based capital	$ 434,207	$ 428,021
Tier one risk based capital to risk weighted assets	0.1048	0.1047
Tier one risk based capital required for capital adequacy	$ 352,118	$ 347,348
Tier one risk based capital required for capital adequacy to risk weighted assets	0.0850	0.0850
Common equity tier one capital	$ 392,532	$ 386,434
Common equity tier one capital to risk weighted assets	9.48%	9.46%
Common equity tier one capital required for capital adequacy	$ 289,980	$ 286,051
Common equity tier one capital required for capital adequacy to risk weighted assets	7.00%	7.00%
Tier one leverage capital	$ 434,207	$ 428,021
Tier one leverage capital to average assets	0.0872	0.0948
Tier one leverage capital required for capital adequacy	$ 199,225	$ 180,529
Tier one leverage capital required for capital adequacy to average assets	0.0400	0.0400
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	$ 513,922	$ 482,106
Capital to risk weighted assets	0.1247	0.1183
Capital required for capital adequacy	$ 432,647	$ 427,877
Capital required for capital adequacy to risk weighted assets	0.1050	0.1050
Capital required to be well capitalized	$ 412,045	$ 407,502
Capital required to be well capitalized to risk weighted assets	0.1000	0.1000
Tier one risk based capital	$ 467,154	$ 453,027
Tier one risk based capital to risk weighted assets	0.1134	0.1112
Tier one risk based capital required for capital adequacy	$ 350,238	$ 346,377
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	$ 329,636	$ 326,002
Tier one risk based capital required to be well capitalized to risk weighted assets	0.0800	0.0800
Common equity tier one capital	$ 467,154	$ 453,027
Common equity tier one capital to risk weighted assets	11.34%	11.12%
Common equity tier one capital required for capital adequacy	$ 288,431	$ 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	$ 267,829	$ 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	$ 467,154	$ 453,027
Tier one leverage capital to average assets	0.0939	0.1006
Tier one leverage capital required for capital adequacy	$ 198,967	$ 180,209
Tier one leverage capital required for capital adequacy to average assets	0.0400	0.0400
Tier one leverage capital required to be well capitalized	$ 248,709	$ 231,166
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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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 1 risk-based capital as defined by regulatory framework.

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