Parent Company Only Financial Information - Condensed Balance Sheets (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
ASSETS
Trading securities	$ 4,576	$ 4,505
Total Assets	2,285,136	2,189,213
Liabilities
Subordinated debentures	20,620	20,620
Total liabilities	2,083,223	2,000,665
Total shareholders' equity	201,913	188,548	$ 164,911	$ 145,364
Total liabilities and shareholders' equity	2,285,136	2,189,213
Parent Company [Member]
ASSETS
Cash	1,557	1,556
Trading securities	434	417
Investment in bank subsidiary	197,226	184,671
Investment in non-bank subsidiaries	24,345	23,720
Deferred tax asset	482	529
Other assets	2,106	2,159
Total Assets	226,150	213,052
Liabilities
Borrowings from subsidiary	1,350	1,350
Subordinated debentures	20,620	20,620
Other liabilities	2,267	2,534
Total liabilities	24,237	24,504
Total shareholders' equity	201,913	188,548
Total liabilities and shareholders' equity	$ 226,150	$ 213,052