Regulatory Capital Requirements and Restrictions (Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations) (Details) $ in Millions	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Regions Financial Corporation [Member]
Basel III Common Equity Tier 1 Capital
Basel III common equity Tier 1, Amount	$ 12,976	$ 12,066
Basel III common equity Tier 1, Ratio	0.1026	0.0960
Tier One Risk Based Capital
Tier 1 Capital, Amount	$ 14,635	$ 13,725
Tier 1 Capital, Ratio	0.1157	0.1091
Total Capital
Total Capital, Amount	$ 16,885	$ 15,767
Total Capital, Ratio	0.1335	0.1254
Leverage Capital
Leverage, Amount	$ 14,635	$ 13,725
Leverage, Ratio	0.0972	0.0890
Regions Bank [Member]
Basel III Common Equity Tier 1 Capital
Basel III common equity Tier 1, Amount	$ 14,136	$ 13,509
Basel III common equity Tier 1, Ratio	0.1122	0.1077
Tier One Risk Based Capital
Tier 1 Capital, Amount	$ 14,136	$ 13,509
Tier 1 Capital, Ratio	0.1122	0.1077
Total Capital
Total Capital, Amount	$ 16,057	$ 15,172
Total Capital, Ratio	0.1274	0.1210
Leverage Capital
Leverage, Amount	$ 14,136	$ 13,509
Leverage, Ratio	0.0944	0.0880
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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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
-Topic 942
-SubTopic 505
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (c)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480696/942-505-50-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 505
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480696/942-505-50-1B

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Amount of total 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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