Regulatory Matters - Summary of Capital Amounts, Tier 1 Risk Based and Tier 1 Leveraged Ratios (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Jan. 01, 2016	Dec. 31, 2015
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier 1 capital (to risk-weighted assets), for capital adequacy purposes ratio	6.00%
Tier 1 capital (to risk-weighted assets), to be well capitalized under prompt corrective action provisions ratio	8.00%
Customers Bancorp, Inc.
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common equity Tier 1 (to risk-weighted-assets), actual amount	$ 628,139		$ 500,624
Tier 1 capital (to risk-weighted assets), actual amount	844,755		556,193
Total capital (to risk-weighted assets), actual amount	966,097		698,323
Tier 1 capital (to average assets), actual amount	$ 844,755		$ 556,193
Common equity Tier 1 (to risk-weighted assets), actual ratio	8.487%		7.61%
Tier 1 capital (to risk-weighted assets), actual ratio	11.414%		8.46%
Total capital (to risk-weighted assets), actual ratio	13.053%		10.62%
Tier 1 capital (to average assets), actual ratio	9.067%		7.16%
Common equity Tier 1 (to risk-weighted assets), for capital adequacy purposes amount	$ 379,306		$ 296,014
Tier 1 capital (to risk-weighted assets), for capital adequacy purposes amount	490,322		394,685
Total capital (to risk-weighted assets), for capital adequacy purposes amount	638,343		526,247
Tier 1 capital (to average assets), for capital adequacy purposes amount	$ 372,652		$ 310,812
Common equity Tier 1 (to risk-weighted assets), for capital adequacy purposes ratio	5.125%	5.125%	4.50%
Tier 1 capital (to risk-weighted assets), for capital adequacy purposes ratio	6.625%	6.625%	6.00%
Total capital (to risk-weighted assets), for capital adequacy purposes ratio	8.625%	8.625%	8.00%
Tier 1 capital (to average assets), for capital adequacy purposes ratio	4.00%		4.00%
Customers Bank
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common equity Tier 1 (to risk-weighted-assets), actual amount	$ 857,421		$ 565,217
Tier 1 capital (to risk-weighted assets), actual amount	857,421		565,217
Total capital (to risk-weighted assets), actual amount	1,003,609		710,864
Tier 1 capital (to average assets), actual amount	$ 857,421		$ 565,217
Common equity Tier 1 (to risk-weighted assets), actual ratio	11.626%		8.62%
Tier 1 capital (to risk-weighted assets), actual ratio	11.626%		8.62%
Total capital (to risk-weighted assets), actual ratio	13.608%		10.85%
Tier 1 capital (to average assets), actual ratio	9.233%		7.30%
Common equity Tier 1 (to risk-weighted assets), for capital adequacy purposes amount	$ 377,973		$ 294,916
Tier 1 capital (to risk-weighted assets), for capital adequacy purposes amount	488,599		393,221
Total capital (to risk-weighted assets), for capital adequacy purposes amount	636,101		524,295
Tier 1 capital (to average assets), for capital adequacy purposes amount	$ 371,466		$ 309,883
Common equity Tier 1 (to risk-weighted assets), for capital adequacy purposes ratio	5.125%	5.125%	4.50%
Tier 1 capital (to risk-weighted assets), for capital adequacy purposes ratio	6.625%	6.625%	6.00%
Total capital (to risk-weighted assets), for capital adequacy purposes ratio	8.625%	8.625%	8.00%
Tier 1 capital (to average assets), for capital adequacy purposes ratio	4.00%		4.00%
Common equity Tier 1 (to risk-weighted assets), to be well capitalized under prompt correction action provisions amount	$ 479,380		$ 425,990
Tier 1 capital (to risk-weighted assets), to be well capitalized under prompt corrective action provisions amount	590,006		524,295
Total capital (to risk-weighted assets), to be well capitalized under prompt corrective action provisions amount	737,508		655,369
Tier 1 capital (to average assets), to be well capitalized under prompt corrective action provisions amount	$ 464,333		$ 387,353
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	8.00%		8.00%
Total capital (to risk-weighted assets), to be well capitalized under prompt corrective action provisions ratio	10.00%		10.00%
Tier 1 capital (to average assets), to be well capitalized under prompt corrective action provisions ratio	5.00%		5.00%