Regulatory Matters - Summary of Capital Amounts and Ratios (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Customers Bancorp, Inc. [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total capital (to risk weighted assets), Actual Amount	$ 406,314	$ 289,035
Tier 1 capital (to risk weighted assets), Actual Amount	377,617	262,719
Tier 1 capital (to average assets), Actual Amount	377,617	262,719
Total capital (to risk weighted assets), Actual Ratio	13.32%	11.26%
Tier 1 capital (to risk weighted assets), Actual Ratio	12.38%	10.23%
Tier 1 capital (to average assets), Actual Ratio	11.20%	9.30%
Total capital (to risk weighted assets), For Capital Adequacy Purposes Amount	244,036	205,443
Tier 1 capital (to risk weighted assets), For Capital Adequacy Purposes Amount	122,018	102,722
Tier 1 capital (to average assets), For Capital Adequacy Purposes Amount	134,895	112,939
Total capital (to risk weighted assets), for Capital Adequacy Purposes Ratio	8.00%	8.00%
Tier 1 capital (to risk weighted assets), For Capital Adequacy Purposes Ratio	4.00%	4.00%
Tier 1 capital (to average assets), For Capital Adequacy Purposes Ratio	4.00%	4.00%
Customers Bank [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total capital (to risk weighted assets), Actual Amount	378,972	244,710
Tier 1 capital (to risk weighted assets), Actual Amount	350,275	218,394
Tier 1 capital (to average assets), Actual Amount	350,275	218,394
Total capital (to risk weighted assets), Actual Ratio	12.43%	9.53%
Tier 1 capital (to risk weighted assets), Actual Ratio	11.49%	8.50%
Tier 1 capital (to average assets), Actual Ratio	10.39%	7.74%
Total capital (to risk weighted assets), For Capital Adequacy Purposes Amount	243,915	205,442
Tier 1 capital (to risk weighted assets), For Capital Adequacy Purposes Amount	121,958	102,721
Tier 1 capital (to average assets), For Capital Adequacy Purposes Amount	134,845	112,896
Total capital (to risk weighted assets), for Capital Adequacy Purposes Ratio	8.00%	8.00%
Tier 1 capital (to risk weighted assets), For Capital Adequacy Purposes Ratio	4.00%	4.00%
Tier 1 capital (to average assets), For Capital Adequacy Purposes Ratio	4.00%	4.00%
Total capital (to risk weighted assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Amount	304,894	256,802
Tier 1 capital (to risk weighted assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Amount	182,937	154,081
Tier 1 capital (to average assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Amount	$ 168,556	$ 141,120
Total capital (to risk weighted assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio	10.00%	10.00%
Tier 1 capital (to risk weighted assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio	6.00%	6.00%
Tier 1 capital (to average assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio	5.00%	5.00%