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Comprehensive Income (Components of Accumulated Other Comprehensive Income) (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance December,				$ 19,788,000					$ 19,788,000
Other Comprehensive Income Loss Reclassification Adjustment From AOCI For Non Credit Other Than Temporary Impaired Securities Net Of Tax									(232,000)	$ (1,085,000)	$ (9,000)
Amount reclassified from AOCI, HTM									377,000	844,000	1,025,000
OCI before reclassifications, Defined Benefit Pension and Post Retirement Plans									1,585,000	(35,189,000)	38,775,000
Amounts reclassified from AOCI,All other									(9,110,000)	(18,762,000)	(15,301,000)
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax									6,185,000	(33,953,000)	41,635,000
Other comprehensive loss	$ (3,386,000)	$ 6,290,000	$ (35,944,000)	3,827,000	$ (29,337,000)	$ (18,887,000)	$ 26,483,000	$ 16,678,000	(29,213,000)	(5,063,000)	(29,189,000)
Balance December,	(9,425,000)				19,788,000				(9,425,000)	19,788,000
Accumulated Other-than-Temporary Impairment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance December,				(514,000)				(1,599,000)	(514,000)	(1,599,000)
OCI before reclassifications									0	0
Other comprehensive loss									232,000	1,085,000
Balance December,	(282,000)				(514,000)				(282,000)	(514,000)	(1,599,000)
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance December,				(60,605,000)				(26,652,000)	(60,605,000)	(26,652,000)
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax									4,600,000	1,236,000
Balance December,	(54,420,000)				(60,605,000)				(54,420,000)	(60,605,000)	(26,652,000)
Accumulated other comprehensive income (loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance December,				19,788,000				24,851,000	19,788,000	24,851,000
OCI before reclassifications									(24,558,000)	12,222,000
Amount reclassified from AOCI									(4,655,000)	(17,285,000)
Other comprehensive loss									(29,213,000)	(5,063,000)	(29,189,000)
Balance December,	(9,425,000)				19,788,000				(9,425,000)	19,788,000	24,851,000
Held-to-maturity Securities [Member] | Accumulated Net Unrealized Investment Gain (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance December,				623,000				1,467,000	623,000	1,467,000
OCI before reclassifications									0	0
Other comprehensive loss									(377,000)	(844,000)
Balance December,	246,000				623,000				246,000	623,000	1,467,000
Available-for-sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance December,				80,284,000				51,635,000	80,284,000	51,635,000
OCI before reclassifications									(26,143,000)	47,411,000
Other comprehensive loss									(35,253,000)	28,649,000
Balance December,	45,031,000				80,284,000				45,031,000	80,284,000	51,635,000
Investments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance December,				$ 80,393,000				$ 51,503,000	80,393,000	51,503,000
OCI before reclassifications									(26,143,000)	47,411,000
Amount reclassified from AOCI									(9,255,000)	(18,521,000)
Other comprehensive loss									(35,398,000)	28,890,000
Balance December,	$ 44,995,000				$ 80,393,000				$ 44,995,000	$ 80,393,000	$ 51,503,000

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Net of tax amount of the reclassification adjustment related to held-to-maturity securities transferred from the available-for-sale category. This amount includes amortization and amounts realized from the disposal of these securities.

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