Condensed Financial Statements of Parent Company - Summary of Condensed Statements of Cash Flows of Parent Company (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash Flows from Operating Activities:
Net income	$ 32,694	$ 23,818	$ 4,034
Adjustments to reconcile net income to net cash used in operating activities:
Increase in other assets	(15,091)	(9,587)	2,257
(Decrease) increase in other liabilities	6,974	4,346	(2,369)
Net Cash Provided by (Used in) Operating Activities	722,035	(1,242,061)	29,903
Cash Flows from Investing Activities:
Purchases of investment securities available for sale	(542,110)	(114,049)	(72,932)
Net Cash Used in Investing Activities	(1,588,015)	262,130	(760,478)
Cash Flows from Financing Activities:
Proceeds from issuance of common stock	97,507	94,586	28,526
Proceeds from issuance of long-term debt	60,336	0	0
Repayment of TARP	0	0	(3,056)
Payment of preferred dividends	0	0	(44)
Exercise and redemption of warrants	264	0	0
Purchase of treasury stock	(7,754)	0	(500)
Net Cash Provided by Financing Activities	913,032	1,092,377	565,421
Net (Decrease) Increase in Cash and Cash Equivalents	47,052	112,446	(165,154)
Cash and Cash Equivalents - Beginning	186,016	73,570	238,724
Cash and Cash Equivalents - Ending	233,068	186,016	73,570
The Customer Bancorp [Member]
Cash Flows from Operating Activities:
Net income	32,694	23,818	4,034
Adjustments to reconcile net income to net cash used in operating activities:
Equity in undistributed earnings of subsidiaries	(35,658)	(25,578)	(4,034)
Increase in other assets	(1,465)	(12)	0
(Decrease) increase in other liabilities	(281)	372	0
Net Cash Provided by (Used in) Operating Activities	(4,710)	(1,400)	0
Cash Flows from Investing Activities:
Purchases of investment securities available for sale	0	(6)	0
Payments for investments in and advances to subsidiaries	(177,068)	(53,500)	(4,420)
Net Cash Used in Investing Activities	(177,068)	(53,506)	(4,420)
Cash Flows from Financing Activities:
Proceeds from issuance of common stock	97,507	94,586	13,000
Proceeds from issuance of long-term debt	60,336	0	0
Repayment of TARP	0	0	(3,037)
Payment of preferred dividends	0	0	(44)
Exercise and redemption of warrants	264	0	0
Purchase of treasury stock	(7,754)	0	(500)
Net Cash Provided by Financing Activities	150,353	94,586	9,419
Net (Decrease) Increase in Cash and Cash Equivalents	(31,425)	39,680	4,999
Cash and Cash Equivalents - Beginning	44,679	4,999	0
Cash and Cash Equivalents - Ending	$ 13,254	$ 44,679	$ 4,999