v3.26.1
REGULATORY CAPITAL - Summary of Capital Amounts, Tier 1 Risk Based and Tier 1 Leveraged Ratios (Detail) - USD ($)
$ in Thousands
Mar. 31, 2026
Dec. 31, 2025
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]    
Common equity Tier 1 capital (to risk weighted assets), Actual Amount $ 2,193,602 $ 2,164,010
Tier 1 capital (to risk weighted assets), Actual Amount 2,193,602 2,164,010
Total capital (to risk weighted assets), Actual Amount 2,532,424 2,563,309
Tier 1 capital (to average assets), Actual Amount $ 2,193,602 $ 2,164,010
Common equity Tier 1 (to risk weighted assets), Actual Ratio 12.893% 12.992%
Tier 1 capital (to risk weighted assets), Actual Ratio 0.12893 0.12992
Total capital (to risk weighted assets), Actual Ratio 0.14884 0.15389
Tier 1 capital (to average assets), Actual Ratio 0.08768 0.08724
Common equity Tier 1 capital (to risk weighted assets), For Capital Adequacy Purposes Amount $ 765,633 $ 749,547
Tier 1 capital (to risk weighted assets), For Capital Adequacy Purposes Amount 1,020,844 999,396
Total capital (to risk weighted assets), For Capital Adequacy Purposes Amount 1,361,126 1,332,528
Tier 1 capital (to average assets), For Capital Adequacy Purposes Amount $ 1,000,743 $ 992,221
Common equity Tier 1 (to risk weighted assets), For Capital Adequacy Purposes Ratio 4.50% 4.50%
Tier 1 capital (to risk weighted assets), For Capital Adequacy Purposes Ratio 0.06000 0.06000
Total capital (to risk weighted assets), For Capital Adequacy Purposes Ratio 0.08000 0.08000
Tier 1 capital (to average assets), For Capital Adequacy Purposes Ratio 0.04000 0.04000
Common equity Tier 1 (to risk weighted assets), for Basel III amount $ 1,190,985 $ 1,165,962
Tier 1 (to risk weighted assets) Required for Basel III amount 1,446,196 1,415,811
Total capital (to risk weighted assets), for Basel III amount 1,786,478 1,748,943
Tier 1 (to risk average assets), for Basel III amount $ 1,000,743 $ 992,221
Common equity Tier 1 (to risk weighted assets), for Basel III ratio 7.00% 7.00%
Tier 1 capital (to risk weighted assets), for Basel III ratio 8.50% 8.50%
Total capital (to risk weighted assets), for Basel III ratio 10.50% 10.50%
Tier 1 capital (to average assets), for Basel III ratio 4.00% 4.00%
Customers Bank    
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]    
Common equity Tier 1 capital (to risk weighted assets), Actual Amount $ 2,341,612 $ 2,203,933
Tier 1 capital (to risk weighted assets), Actual Amount 2,341,612 2,203,933
Total capital (to risk weighted assets), Actual Amount 2,508,820 2,431,744
Tier 1 capital (to average assets), Actual Amount $ 2,341,612 $ 2,203,933
Common equity Tier 1 (to risk weighted assets), Actual Ratio 13.784% 13.252%
Tier 1 capital (to risk weighted assets), Actual Ratio 0.13784 0.13252
Total capital (to risk weighted assets), Actual Ratio 0.14768 0.14621
Tier 1 capital (to average assets), Actual Ratio 0.09367 0.08895
Common equity Tier 1 capital (to risk weighted assets), For Capital Adequacy Purposes Amount $ 764,460 $ 748,412
Tier 1 capital (to risk weighted assets), For Capital Adequacy Purposes Amount 1,019,280 997,883
Total capital (to risk weighted assets), For Capital Adequacy Purposes Amount 1,359,040 1,330,510
Tier 1 capital (to average assets), For Capital Adequacy Purposes Amount $ 999,964 $ 991,061
Common equity Tier 1 (to risk weighted assets), For Capital Adequacy Purposes Ratio 4.50% 4.50%
Tier 1 capital (to risk weighted assets), For Capital Adequacy Purposes Ratio 0.06000 0.06000
Total capital (to risk weighted assets), For Capital Adequacy Purposes Ratio 0.08000 0.08000
Tier 1 capital (to average assets), For Capital Adequacy Purposes Ratio 0.04000 0.04000
Common equity Tier 1 Capital (to risk weighted assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Amount $ 1,104,220 $ 1,081,040
Tier 1 capital (to risk weighted assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Amount 1,359,040 1,330,510
Total capital (to risk weighted assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Amount 1,698,800 1,663,138
Tier 1 capital (to average assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Amount $ 1,249,955 $ 1,238,827
Common equity Tier 1 (to risk weighted assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio 6.50% 6.50%
Tier 1 capital (to risk weighted assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio 0.08000 0.08000
Total capital (to risk weighted assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio 0.10000 0.10000
Tier 1 capital (to average assets), To Be Well Capitalized Under Prompt Corrective Action Provisions Ratio 0.05000 0.05000
Common equity Tier 1 (to risk weighted assets), for Basel III amount $ 1,189,160 $ 1,164,197
Tier 1 (to risk weighted assets) Required for Basel III amount 1,443,980 1,413,667
Total capital (to risk weighted assets), for Basel III amount 1,783,740 1,746,295
Tier 1 (to risk average assets), for Basel III amount $ 999,964 $ 991,061
Common equity Tier 1 (to risk weighted assets), for Basel III ratio 7.00% 7.00%
Tier 1 capital (to risk weighted assets), for Basel III ratio 8.50% 8.50%
Total capital (to risk weighted assets), for Basel III ratio 10.50% 10.50%
Tier 1 capital (to average assets), for Basel III ratio 4.00% 4.00%