Accumulated Other Comprehensive Income (Loss) (''AOCI'') - Changes in AOCI by Component (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Changes in AOCI by Component
Balance at the beginning of the period, net of taxes			$ (6,220)
Net current period other comprehensive income (loss), net of taxes	$ 1,356	$ (1,954)	4,078	$ (1,420)
Balance at the end of the period, net of taxes	(2,142)		(2,142)
Accumulated Other Comprehensive Income / (Loss)
Changes in AOCI by Component
Balance at the beginning of the period, net of taxes	(3,498)	(1,317)	(6,220)	(1,851)
Other comprehensive income (loss) before reclassification, net of taxes	1,574	(1,976)	4,381	(1,483)
Amounts reclassified from other comprehensive income (loss), net of taxes	(218)	22	(303)	63
Net current period other comprehensive income (loss), net of taxes	1,356	(1,954)	4,078	(1,420)
Balance at the end of the period, net of taxes	(2,142)	(3,271)	(2,142)	(3,271)
Unrealized Gains on Available-for-Sale Securities and I/O Strips
Changes in AOCI by Component
Balance at the beginning of the period, net of taxes	3,792	4,180	1,090	3,666
Other comprehensive income (loss) before reclassification, net of taxes	1,579	(1,974)	4,386	(1,460)
Amounts reclassified from other comprehensive income (loss), net of taxes	(201)		(306)
Net current period other comprehensive income (loss), net of taxes	1,378	(1,974)	4,080	(1,460)
Balance at the end of the period, net of taxes	5,170	2,206	5,170	2,206
Unamortized Unrealized Gain on Available-for-Sale Securities Reclassified to Held-to-Maturity
Changes in AOCI by Component
Balance at the beginning of the period, net of taxes	395	427	403	435
Amounts reclassified from other comprehensive income (loss), net of taxes	(44)	(8)	(52)	(16)
Net current period other comprehensive income (loss), net of taxes	(44)	(8)	(52)	(16)
Balance at the end of the period, net of taxes	351	419	351	419
Defined Benefit Pension Plan Items
Changes in AOCI by Component
Balance at the beginning of the period, net of taxes	(7,685)	(5,924)	(7,713)	(5,952)
Other comprehensive income (loss) before reclassification, net of taxes	(5)	(2)	(5)	(23)
Amounts reclassified from other comprehensive income (loss), net of taxes	27	30	55	79
Net current period other comprehensive income (loss), net of taxes	22	28	50	56
Balance at the end of the period, net of taxes	$ (7,663)	$ (5,896)	$ (7,663)	$ (5,896)

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

No definition available.

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- Definition

Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=36458714&loc=d3e637-108580

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-Publisher FASB
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-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 31
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Reference 5: http://www.xbrl.org/2003/role/presentationRef
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Amount after tax, before reclassification adjustments, of other comprehensive income (loss), attributable to parent.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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Amount after tax of other comprehensive income (loss) attributable to parent entity.

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Amount after tax of reclassification adjustments of other comprehensive income (loss) attributable to parent.

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