Regulatory Capital Requirements and Restrictions (Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations) (Details) $ in Millions	Dec. 31, 2022 USD ($)	Sep. 30, 2022	Dec. 31, 2021 USD ($)
Leverage Capital
Banking Regulation, Capital Conservation Buffer, Capital Conserved, Minimum	0.0250	0.025
Regions Financial Corporation [Member]
Basel III Common Equity Tier 1 Capital
Basel III common equity Tier 1, Amount	$ 12,066		$ 10,844
Basel III common equity Tier 1, Ratio	0.0960		0.0957
Tier One Risk Based Capital
Tier 1 Capital, Amount	$ 13,725		$ 12,503
Tier 1 Capital, Ratio	0.1091		0.1103
Total Capital
Total Capital, Amount	$ 15,767		$ 14,441
Total Capital, Ratio	0.1254		0.1274
Leverage Capital
Leverage, Amount	$ 13,725		$ 12,503
Leverage, Ratio	0.0890		0.0808
Regions Bank [Member]
Basel III Common Equity Tier 1 Capital
Basel III common equity Tier 1, Amount	$ 13,509		$ 12,478
Basel III common equity Tier 1, Ratio	0.1077		0.1105
Tier One Risk Based Capital
Tier 1 Capital, Amount	$ 13,509		$ 12,478
Tier 1 Capital, Ratio	0.1077		0.1105
Total Capital
Total Capital, Amount	$ 15,172		$ 13,985
Total Capital, Ratio	0.1210		0.1238
Leverage Capital
Leverage, Amount	$ 13,509		$ 12,478
Leverage, Ratio	0.0880		0.0809
Standardized Approach [Member] \| Regions Financial Corporation [Member]
Basel III Common Equity Tier 1 Capital
Basel III common equity Tier 1,Minimum Requirement	0.0450		0.0450
Base III common equity, Tie 1, minimum requirement plus SCB	7.00%		7.00%
Tier One Risk Based Capital
Tier 1 Capital, Minimum Requirement	0.0600		0.0600
Tier 1 Capital, Minimum Requirement Plus SCB	8.50%		8.50%
Tier 1 Capital, To Be Well Capitalized	0.0600		0.0600
Total Capital
Total Capital, Minimum Requirement	0.0800		0.0800
Total Capital, Minimum Requirement Plus SCB	10.50%		10.50%
Total Capital, To Be Well Capitalized	0.1000		0.1000
Leverage Capital
Leverage, Minimum Requirement	0.0400		0.0400
Leverage, Minimum Requirement Plus SCB	4.00%		4.00%
Standardized Approach [Member] \| Regions Bank [Member]
Basel III Common Equity Tier 1 Capital
Basel III common equity Tier 1,Minimum Requirement	0.0450		0.0450
Base III common equity, Tie 1, minimum requirement plus SCB	7.00%		7.00%
Basel III common equity Tier 1, To Be Well Capitalized	0.0650		0.0650
Tier One Risk Based Capital
Tier 1 Capital, Minimum Requirement	0.0600		0.0600
Tier 1 Capital, Minimum Requirement Plus SCB	8.50%		8.50%
Tier 1 Capital, To Be Well Capitalized	0.0800		0.0800
Total Capital
Total Capital, Minimum Requirement	0.0800		0.0800
Total Capital, Minimum Requirement Plus SCB	10.50%		10.50%
Total Capital, To Be Well Capitalized	0.1000		0.1000
Leverage Capital
Leverage, Minimum Requirement	0.0400		0.0400
Leverage, Minimum Requirement Plus SCB	4.00%		4.00%
Leverage, To Be Well Capitalized	0.0500		0.0500

Banking Regulation, Common Equity Tier 1 Risk-Based Capital Ratio, Capital Adequacy, Minimum Plus SCB

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Minimum capital conservation buffer percentage required to avoid restriction on payout amount of eligible retained income as defined by regulatory framework.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 505
-Section 50
-Paragraph 1
-Subparagraph (c)(1)
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Ratio of minimum Common Equity Tier 1 risk-based capital to risk-weighted assets required for capital adequacy as defined by regulatory framework.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-URI https://asc.fasb.org/extlink&oid=117337116&loc=SL5958570-112826

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Amount of total capital as defined by regulatory framework.

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Amount of Tier 1 leverage capital as defined by regulatory framework.

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Ratio of minimum Tier 1 leverage capital to average assets categorized as well capitalized as defined by regulatory framework for prompt corrective action.

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