Consolidated Statements of Comprehensive Income (unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Statement of Comprehensive Income [Abstract]
Net income	$ 6,166	$ 5,706	$ 17,050	$ 16,237
Unrealized gains (losses) on securities:
Unrealized (losses) gains arising during period	27	1,004	(2)	1,509
Less: reclassification adjustment for gains included in net income	(31)		(102)
Total unrealized (losses) gains on securities	(4)	1,004	(104)	1,509
Accretion of net unrealized losses transferred	935	792	2,697	2,524
Defined benefit pension plans:
Amortization of prior service cost and loss included in net periodic benefit cost	213	56	639	169
Other comprehensive income (loss)	1,144	1,852	3,232	4,202
Comprehensive income (loss)	$ 7,310	$ 7,558	$ 20,282	$ 20,439