Regulatory Capital - Narrative (Details)	Dec. 31, 2020
Regulatory Capital [Abstract]
Maximum buffer, percent of risk weighted assets for 2019 and thereafter	2.50%

Capital Conservation Buffer to Risk Weighted Assets, Year Four and Thereafter

No definition available.

Name:	cubi_CapitalConservationBuffertoRiskWeightedAssetsYearFourandThereafter
Namespace Prefix:	cubi_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant