Accumulated Other Comprehensive Income Changes in Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Equity [Abstract]
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, before Tax	$ 26,193	$ 15,371
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Tax	(9,167)	(5,379)
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax	17,026	9,992
Other Comprehensive Income (Loss), Reclassification Adjustment for Sale of Securities Included in Net Income, before Tax	(947)	(4,145)
Other Comprehensive Income (Loss), Reclassification Adjustment for Sale of Securities Included in Net Income, Tax	331	1,450
Other Comprehensive Income (Loss), Reclassification Adjustment for Sale of Securities Included in Net Income, Net of Tax	(616)	(2,695)
Other than Temporary Impairment Losses, Investments, Portion in Other Comprehensive Income (Loss), before Tax, Including Portion Attributable to Noncontrolling Interest		192
Other than Temporary Impairment Losses, Investments, Portion in Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent		(67)
Other than Temporary Impairment Losses, Investments, Portion in Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	0	125
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax	6	52
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Tax	(2)	(18)
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax	4	34
Other Comprehensive Income (Loss), Amortization, Pension and Other Postretirement Benefit Plans, Net Prior Service Cost (Credit) Recognized in Net Periodic Benefit Cost, before Tax	717	717
Other Comprehensive Income (Loss), Amortization, Pension and Other Postretirement Benefit Plans, Net Prior Service Cost Recognized in Net Periodic Pension Cost, Tax Effect	(251)	(251)
Other Comprehensive Income (Loss), Amortization, Pension and Other Postretirement Benefit Plans, Net Prior Service Cost Recognized in Net Periodic Pension Cost, Net of Tax	466	466
Other Comprehensive Income (Loss), before Tax	25,969	12,187
Other Comprehensive Income (Loss), Tax	(9,089)	(4,265)
Other Comprehensive Income	$ 16,880	$ 7,922