Other Comprehensive Income (Loss) (Component Of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015	Dec. 31, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income before reclassifications	$ 11,680	$ 7,859
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax	0	0
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI for Write-down of Securities, before Tax	0	0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0	0
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax	11,680	7,859
Other comprehensive income (loss)	11,680	7,859
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, before Reclassification Adjustments, Net of Tax	11,680	7,859
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, before Reclassification Adjustments, Net of Tax		0
Changes in pension plan assets and benefit obligations, Net-of-tax amount	(15,351)	(14,865)	$ 15,351	$ 14,865
Unrealized gains on available-for-sale securities, Net-of-tax amount	11,388	9,116	(292)	1,257
Total accumulated other comprehensive income (loss), Net-of-tax amount	(3,963)	$ (5,749)	$ (15,643)	$ (13,608)
Other Comprehensive (Income) Loss, Reclassification Adjustment from AOCI for Write-down of Securities, before Tax	$ 0