Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Other comprehensive income, net of tax:
Unrealized net holding (losses) gains arising during the period, pre-tax amounts	$ (8,618)	$ (3,159)	$ 18,069
Reclassification adjustment for net gains (losses) related to securities available for sale included in net income, pre-tax amounts	644	(3,087)	(92)
Unrealized gains on derivatives (cash flow hedged) (pre-tax amounts)	2,901	0	0
Amortization of unrealized net gains and losses related to the reclassification of available for sale investment securities to held to maturity, pre-tax amounts	(1,094)	(1,311)	(421)
Amortization of prior service cost and actuarial gains, pre-tax amounts	2,370	2,239	75
Decrease (increase) in unrecognized actuarial loss, pre-tax amounts	$ 3,154	$ (6,144)	$ (19,245)