Other Comprehensive Income (Details 1) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accumulated balances for component of other comprehensive income, net of tax
Unrealized gains on securities	$ 7,363	$ 9,490	$ 16,500
Non-credit related portion of other-than-temporary impairment on securities	(9,313)	(16,719)	(16,735)
Unrealized losses on derivative instruments	(995)	(1,355)	(1,882)
Unrecognized losses on defined benefit pension and post-retirement benefit plans obligations	(7,566)	(7,320)	(7,418)
Total accumulated other comprehensive loss	$ (10,511)	$ (15,904)	$ (9,535)

Accumulated appreciation or loss, net of tax, in value of the total of available-for-sale securities at the end of an accounting period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Accumulated change, net of tax, in accumulated gains and losses from derivative instruments designated and qualifying as the effective portion of cash flow hedges. Includes an entity's share of an equity investee's Increase or Decrease in deferred hedging gains or losses.

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Amount, after tax, of accumulated other comprehensive (income) loss for defined benefit plan, that has not been recognized in net periodic benefit cost (credit).

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Total of accumulated other comprehensive loss related to that portion of other than temporary impairment (OTTI) due to factors other than credit losses on debt securities categorized either as available-for-sale or held-to-maturity that an entity does not intend to sell and which it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis of the debt security. The amount represented by this item is net of tax, as applicable.

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