Significant Accounting Policies (Accumulated Other Comprehensive Income) (Details) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ (32,867,000)	$ 27,000,000
Other comprehensive income (loss) before reclassifications	18,500,000	(5,900,000)
Amounts reclassified from accumulated other comprehensive (loss) income	(100,000)	(10,800,000)
Other comprehensive income (loss), net of tax	18,357,000	(16,708,000)
Ending balance	(14,510,000)	10,300,000
Unrealized Gains (Losses) on investments available-for-sale [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(28,300,000)	38,000,000
Other comprehensive income (loss) before reclassifications	18,500,000	(5,900,000)
Amounts reclassified from accumulated other comprehensive (loss) income	(200,000)	(11,200,000)
Other comprehensive income (loss), net of tax	18,300,000	(17,100,000)
Ending balance	(10,000,000)	20,900,000
Defined Benefit Pension Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(4,600,000)	(11,000,000)
Other comprehensive income (loss) before reclassifications	0	0
Amounts reclassified from accumulated other comprehensive (loss) income	100,000	400,000
Other comprehensive income (loss), net of tax	100,000	400,000
Ending balance	$ (4,500,000)	$ (10,600,000)