REGULATORY MATTERS - Narrative (Details)	Dec. 31, 2025	Dec. 31, 2024
Mortgage Banking [Abstract]
Required Minimum Capital	9.00%	9.00%

The minimum common equity tier 1 ratio (CET1 divided by risk-weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action.

No definition available.

Name:	cfg_CommonEquityTier1RequiredForCapitalAdequacyToRiskWeightedAssets
Namespace Prefix:	cfg_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant