Accumulated Other Comprehensive Income (Changes in AOCI by Component) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	[1]	$ (6,295)	$ 5,621
Other comprehensive income before reclassifications	[1]	18,770	9,096
Amounts reclassified from accumulated other comprehensive income (loss) (2)	[1]	(132)	(431)
Net current-period other comprehensive income	[1]	18,638	8,665
Ending balance	[1]	12,343	14,286
Unrealized Gains and Losses on Available-for-Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	[1]	386	7,462
Other comprehensive income before reclassifications	[1]	18,770	9,376
Amounts reclassified from accumulated other comprehensive income (loss) (2)	[1]	(238)	(459)
Net current-period other comprehensive income	[1]	18,532	8,917
Ending balance	[1]	18,918	16,379
Unrealized Gains and Losses on Pension Plan Liability [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	[1]	(6,681)	(1,841)
Other comprehensive income before reclassifications	[1]	0	(280)
Amounts reclassified from accumulated other comprehensive income (loss) (2)	[1]	106	28
Net current-period other comprehensive income	[1]	106	(252)
Ending balance	[1]	$ (6,575)	$ (2,093)

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