Parent Company Only Financial Information - Condensed Balance Sheets (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Assets
Trading securities	$ 7,786	$ 7,150
Total Assets	3,221,521	2,768,773
Liabilities
Subordinated debentures	70,620	70,620
Total liabilities	2,958,691	2,524,863
Total shareholders’ equity	262,830	243,910	$ 211,784	$ 201,913
Total Liabilities and Shareholders’ Equity	3,221,521	2,768,773
Parent Company
Assets
Cash	355	1,556
Trading securities	623	580
Investment in bank subsidiary	310,574	290,156
Investment in non-bank subsidiaries	20,686	21,781
Deferreds and current receivable	1,459	2,055
Other assets	1,749	2,059
Total Assets	335,446	318,187
Liabilities
Borrowings from subsidiary	200	1,400
Subordinated debentures	70,620	70,620
Other liabilities	1,796	2,257
Total liabilities	72,616	74,277
Total shareholders’ equity	262,830	243,910
Total Liabilities and Shareholders’ Equity	$ 335,446	$ 318,187