REGULATORY MATTERS - Narrative (Details)	Dec. 31, 2019	Dec. 31, 2018
Banking and Thrift [Abstract]
Minimum Capital Adequacy	7.00%	6.375%

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:	num:percentItemType
Balance Type:	na
Period Type:	instant