Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2019	Feb. 25, 2020	Jun. 30, 2019
Entity Information [Line Items]
Document Type	10-K
Document Annual Report	true
Document Transition Report	false
Document Period End Date	Dec. 31, 2019
Entity File Number	001-35542
Entity Registrant Name	Customers Bancorp, Inc.
Entity Incorporation, State or Country Code	PA
Entity Tax Identification Number	27-2290659
Entity Address, Address Line One	1015 Penn Avenue
Entity Address, Address Line Two	Suite 103
Entity Address, City or Town	Wyomissing
Entity Address, State or Province	PA
Entity Address, Postal Zip Code	19610
City Area Code	610
Local Phone Number	933-2000
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 605,709,575
Entity Common Stock, Shares Outstanding		31,381,499
Entity Central Index Key	0001488813
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Amendment Flag	false
Documents Incorporated by Reference	Portions of the registrant’s definitive proxy statement to be delivered to shareholders in connection with the 2020 Annual Meeting of Shareholders are incorporated by reference into Part III of this Annual Report.
Voting Common Stock, par value $1.00 per share | New York Stock Exchange
Entity Information [Line Items]
Title of 12(b) Security	Voting Common Stock, par value $1.00 per share
Trading Symbol	CUBI
Security Exchange Name	NYSE
Fixed-to-Floating Rate Non-Cumulative Perpetual Preferred Stock, Series C, par value $1.00 per share | New York Stock Exchange
Entity Information [Line Items]
Title of 12(b) Security	Fixed-to-Floating Rate Non-Cumulative PerpetualPreferred Stock, Series C, par value $1.00 per share
Trading Symbol	CUBI/PC
Security Exchange Name	NYSE
Fixed-to-Floating Rate Non-Cumulative Perpetual Preferred Stock, Series D, par value $1.00 per share | New York Stock Exchange
Entity Information [Line Items]
Title of 12(b) Security	Fixed-to-Floating Rate Non-Cumulative PerpetualPreferred Stock, Series D, par value $1.00 per share
Trading Symbol	CUBI/PD
Security Exchange Name	NYSE
Fixed-to-Floating Rate Non-Cumulative Perpetual Preferred Stock, Series E, par value $1.00 per share | New York Stock Exchange
Entity Information [Line Items]
Title of 12(b) Security	Fixed-to-Floating Rate Non-Cumulative PerpetualPreferred Stock, Series E, par value $1.00 per share
Trading Symbol	CUBI/PE
Security Exchange Name	NYSE
Fixed-to-Floating Rate Non-Cumulative Perpetual Preferred Stock, Series F, par value $1.00 per share | New York Stock Exchange
Entity Information [Line Items]
Title of 12(b) Security	Fixed-to-Floating Rate Non-Cumulative PerpetualPreferred Stock, Series F, par value $1.00 per share
Trading Symbol	CUBI/PF
Security Exchange Name	NYSE
5.375% Subordinated Notes due 2034 | New York Stock Exchange
Entity Information [Line Items]
Title of 12(b) Security	5.375% Subordinated Notes due 2034
Trading Symbol	CUBB
Security Exchange Name	NYSE