Accumulated Other Comprehensive Income (Changes in AOCI by Component) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	[1]	$ (18,999)	$ (6,295)
Other comprehensive income before reclassifications	[1]	6,306	18,770
Amounts reclassified from accumulated other comprehensive income	[1]	87	(132)
Net current-period other comprehensive income	[1]	6,393	18,638
Ending balance	[1]	(12,606)	12,343
Unrealized Gains and Losses on Available-for-Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	[1]	(12,704)	386
Other comprehensive income before reclassifications	[1]	1,702	18,770
Amounts reclassified from accumulated other comprehensive income	[1]	0	(238)
Net current-period other comprehensive income	[1]	1,702	18,532
Ending balance	[1]	(11,002)	18,918
Unrealized Gains and Losses on Pension Plan Liability [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	[1]	(6,295)	(6,681)
Other comprehensive income before reclassifications	[1]	4,604	0
Amounts reclassified from accumulated other comprehensive income	[1]	87	106
Net current-period other comprehensive income	[1]	4,691	106
Ending balance	[1]	$ (1,604)	$ (6,575)

[1] All amounts are net of tax. Amounts in parenthesis indicate debits.