Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Deferred tax assets:
Defined postretirement benefit obligation	$ 11,049	$ 10,327
Allowance for loan losses	7,815	7,728
Federal net operating loss carryforwards	2,397
Stock compensation	2,008	1,693
Accrued expenses	1,689	1,446
State income taxes	889	213
Premises and equipment	945	702
California net operating loss carryforwards	591
Split-dollar life insurance benefit plan	107	112
Tax credit carryforwards	57	2,441
Loans		2
Nonaccrual interest		25
Other	742	359
Total deferred tax assets	28,289	25,048
Deferred tax liabilities:
Intangible assets	(2,101)	(1,334)
Loan fees	(1,331)	(1,131)
Prepaid expenses	(1,022)	(464)
I/O strips	(574)	(621)
Securities available-for-sale	(505)	(2,351)
FHLB stock	(245)	(245)
Other	(293)	(375)
Total deferred tax liabilities	(6,071)	(6,521)
Net deferred tax assets	$ 22,218	$ 18,527