Accumulated Other Comprehensive Income Changes in Other Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, before Tax	$ (56,858)	$ (16,467)	$ (56,666)	$ (9,415)
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Tax	19,900	5,763	19,833	3,295
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax	(36,958)	(10,704)	(36,833)	(6,120)
Other Comprehensive Income (Loss), Reclassification Adjustment for Sale of Securities Included in Net Income, before Tax	(2,865)	(1,538)	(5,338)	(2,789)
Other Comprehensive Income (Loss), Reclassification Adjustment for Sale of Securities Included in Net Income, Tax	1,003	539	1,868	977
Other Comprehensive Income (Loss), Reclassification Adjustment for Sale of Securities Included in Net Income, Net of Tax	(1,862)	(999)	(3,470)	(1,812)
Other than Temporary Impairment Losses, Investments, Portion in Other Comprehensive Income (Loss), before Tax, Including Portion Attributable to Noncontrolling Interest	546	(265)	2,212	(57)
Other than Temporary Impairment Losses, Investments, Portion in Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	(191)	93	(774)	20
Other than Temporary Impairment Losses, Investments, Portion in Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	355	(172)	1,438	(37)
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax	51	52	105	104
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Tax	(17)	(18)	(37)	(36)
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax	34	34	68	68
Other Comprehensive Income (Loss), Amortization, Pension and Other Postretirement Benefit Plans, Net Prior Service Cost (Credit) Recognized in Net Periodic Benefit Cost, before Tax	504	330	1,009	659
Other Comprehensive Income (Loss), Amortization, Pension and Other Postretirement Benefit Plans, Net Prior Service Cost Recognized in Net Periodic Pension Cost, Tax Effect	(176)	(116)	(353)	(231)
Other Comprehensive Income (Loss), Amortization, Pension and Other Postretirement Benefit Plans, Net Prior Service Cost Recognized in Net Periodic Pension Cost, Net of Tax	328	214	656	428
Other Comprehensive Income (Loss), before Tax	(58,622)	(17,888)	(58,678)	(11,498)
Other Comprehensive Income (Loss), Tax	20,519	6,261	20,537	4,025
Other Comprehensive Income (Loss)	$ (38,103)	$ (11,627)	$ (38,141)	$ (7,473)