Significant Accounting Policies (Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ (13,500)	$ (500)	$ (3,261)	$ (32,900)
Other comprehensive income (loss) before reclassifications	7,300	1,300	(2,300)	35,000
Amounts reclassified from accumulated other comprehensive (loss) income	500	(100)	(100)	(1,400)
Other comprehensive income (loss), net of tax	7,851	1,227	(2,427)	33,643
Ending balance	(5,688)	700	(5,688)	700
Unrealized Gains (Losses) on investments available-for-sale [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(2,800)	3,900	8,200	(28,300)
Other comprehensive income (loss) before reclassifications	7,300	1,300	(2,300)	35,000
Amounts reclassified from accumulated other comprehensive (loss) income	100	(200)	(1,300)	(1,700)
Other comprehensive income (loss), net of tax	7,400	1,100	(3,600)	33,300
Ending balance	4,600	5,000	4,600	5,000
Defined Benefit Pension Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(10,700)	(4,400)	(11,500)	(4,600)
Other comprehensive income (loss) before reclassifications	0	0	0	0
Amounts reclassified from accumulated other comprehensive (loss) income	400	100	1,200	300
Other comprehensive income (loss), net of tax	400	100	1,200	300
Ending balance	$ (10,300)	$ (4,300)	$ (10,300)	$ (4,300)