Accumulated Other Comprehensive Income Changes in Other Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, before Tax	$ 16,668	$ (2,886)	$ 7,252	$ 23,297
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Tax	(5,834)	1,010	(2,538)	(8,154)
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax	10,834	(1,876)	4,714	15,143
Other Comprehensive Income (Loss), Reclassification Adjustment for Sale of Securities Included in Net Income, before Tax	(43)	443	(2,831)	(1,506)
Other Comprehensive Income (Loss), Reclassification Adjustment for Sale of Securities Included in Net Income, Tax	15	(155)	991	527
Other Comprehensive Income (Loss), Reclassification Adjustment for Sale of Securities Included in Net Income, Net of Tax	(28)	288	(1,840)	(979)
Other than Temporary Impairment Losses, Investments, Portion in Other Comprehensive Income (Loss), before Tax, Including Portion Attributable to Noncontrolling Interest	417	(834)	360	288
Other than Temporary Impairment Losses, Investments, Portion in Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent	(146)	292	(126)	(101)
Other than Temporary Impairment Losses, Investments, Portion in Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	271	(542)	234	187
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax	52	52	157	157
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Tax	(18)	(18)	(55)	(55)
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax	34	34	102	102
Other Comprehensive Income (Loss), Amortization, Pension and Other Postretirement Benefit Plans, Net Prior Service Cost (Credit) Recognized in Net Periodic Benefit Cost, before Tax	329	(20)	988	(57)
Other Comprehensive Income (Loss), Amortization, Pension and Other Postretirement Benefit Plans, Net Prior Service Cost Recognized in Net Periodic Pension Cost, Tax Effect	(115)	7	(346)	20
Other Comprehensive Income (Loss), Amortization, Pension and Other Postretirement Benefit Plans, Net Prior Service Cost Recognized in Net Periodic Pension Cost, Net of Tax	214	(13)	642	(37)
Other Comprehensive Income (Loss), before Tax	17,423	(3,245)	5,926	22,179
Other Comprehensive Income (Loss), Tax	(6,098)	1,136	(2,074)	(7,763)
Other Comprehensive Income (Loss)	$ 11,325	$ (2,109)	$ 3,852	$ 14,416