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Comprehensive Income (Components of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance, December 31, 2016			$ (15,950)
Amounts reclassified into net income: Non-credit OTTI			0
OCI before reclassifications, Defined Benefit Pension and Post Retirement Plans			0
Amount reclassified into net income: Net actuarial loss	$ 330	$ 985	660	$ 1,971
Amounts reclassified from AOCI, HTM related	(28)	(12)	(60)	(59)
Amounts reclassified from AOCI, All Other	(1,225)	(1,145)	(244)	609
Other comprehensive income	22,407	36,010	40,447	81,432
Other Comprehensive Income, Defined Benefit Pension and Post Retirement Plans, Adjustment, Net of Tax	330	$ 985	660	1,971
Ending Balance, June 30, 2017	24,497		24,497
Available-for-sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance, December 31, 2016			42,170
OCI before reclassifications			40,087
Other comprehensive income			39,843
Ending Balance, June 30, 2017	82,013		82,013
Investments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance, December 31, 2016			42,122
OCI before reclassifications			40,091
Amounts reclassified from AOCI			(304)
Other comprehensive income			39,787
Ending Balance, June 30, 2017	81,909		81,909
Accumulated Other-than-Temporary Impairment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance, December 31, 2016			(150)
OCI before reclassifications			4
Other comprehensive income			4
Ending Balance, June 30, 2017	(146)		(146)
Accumulated Net Unrealized Investment Gain (Loss) [Member] | Held-to-maturity Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance, December 31, 2016			102
OCI before reclassifications			0
Other comprehensive income			(60)
Ending Balance, June 30, 2017	42		42
Accumulated Defined Benefit Plans Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance, December 31, 2016			(58,072)
Amount reclassified into net income: Net actuarial loss			660
Ending Balance, June 30, 2017	(57,412)		(57,412)
Accumulated other comprehensive income (loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance, December 31, 2016			(15,950)
OCI before reclassifications			40,091
Amounts reclassified from AOCI			356
Other comprehensive income			40,447	$ 81,432
Ending Balance, June 30, 2017	$ 24,497		$ 24,497

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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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