Condensed Financial Statements of Parent Company - Summary of Condensed Balance Sheets of Parent Company (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
ASSETS
Cash in subsidiary bank	$ 264,593	$ 371,023	$ 233,068	$ 186,016
LIABILITIES AND SHAREHOLDERS’ EQUITY
Other borrowings	88,250	88,250
Total liabilities	7,847,411	6,382,225
Shareholders’ equity	553,902	443,145	386,623	269,475
Total liabilities and shareholders’ equity	8,401,313	6,825,370
The Customer Bancorp
ASSETS
Cash in subsidiary bank	54,567	16,465	$ 13,254	$ 44,679
Investment securities available for sale, at fair value	5	5
Investments in and receivables due from subsidiaries	583,875	509,465
Other assets	4,190	6,678
Total assets	642,637	532,613
LIABILITIES AND SHAREHOLDERS’ EQUITY
Other borrowings	88,250	88,250
Other liabilities	485	1,218
Total liabilities	88,735	89,468
Shareholders’ equity	553,902	443,145
Total liabilities and shareholders’ equity	$ 642,637	$ 532,613