Consolidated Statements of Comprehensive Income (unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Other comprehensive income (loss), net of tax:
Unrealized net holding (losses) gains arising during the period, pre-tax amounts	$ 836	$ 13,211
Reclassification adjustment for net gains (losses) related to securities available for sale included in net income, pre-tax amounts	0	29
Reclassification adjustment for an impairment write-down of equity security, pre-tax amounts	1,312	0
Unrealized gains on derivatives (cash flow hedged) (pre-tax amounts)	331	0
Amortization of unrealized net gains related to the reclassification of available for sale investment securities to held to maturity, pre-tax amounts	238	296
Amortization of prior service cost and actuarial loss, pre-tax amounts	$ 435	$ 512