Changes and Reclassifications Out of Accumulated Other Comprehensive Income Schedule of Accumulated Other Comprehensive Income(Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended			9 Months Ended		12 Months Ended
	Sep. 30, 2014	Jun. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2012	Dec. 31, 2013	Jun. 30, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive (Income) Loss, Amortization Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Prior Service Cost (Credit), before Tax	$ (516)		$ 0	$ (1,614)	$ 0
Other Comprehensive Income (Loss), Amortization Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Prior Service (Cost) Credit, Tax	(181)		0	(565)	0
Other Comprehensive Income (Loss), Amortization Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Prior Service (Cost) Credit, Net of Tax	(335)		0	(1,049)	0
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, before Tax	0		0	0	0
Accumulated Other Comprehensive Income (Loss), before Tax	(76,280)		(128,634)	(76,280)	(128,634)
accumulated other comprehensive income, tax	(26,697)		(45,021)	(26,697)	(45,021)
Accumulated other comprehensive loss	(49,583)		(83,613)	(49,583)	(83,613)		(66,876)
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, before Tax	(16,207)		(17,491)	24,293	(104,853)
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Tax	(5,672)		(6,123)	8,503	(36,699)
Other Comprehensive Income (Loss), Arising During Period, Net of Tax	(10,535)		(11,368)	15,790	(68,154)
Other Comprehensive Income (Loss), Transfers from Held-to-maturity to Available-for-Sale Securities, before Tax	(563)		(534)	(1,551)	(1,654)
Other Comprehensive Income (Loss), Transfers from Held-to-maturity to Available-for-Sale Securities, Tax	(197)		(187)	(543)	(579)
Other Comprehensive Income (Loss), Transfers from Held-to-maturity to Available-for-Sale Securities, Net of Tax	(366)		(347)	(1,008)	(1,075)
Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax	14		(1)	150	2,802
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Tax	5		0	53	981
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Net of Tax	9		(1)	97	1,821
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax	(53,800)	(55,084)	(110,188)	(53,800)	(110,188)	(110,188)	(57,812)	(110,188)
Accumulated other comprehensive income reclassifications, benefit plan, tax	(18,829)	(19,279)	(38,565)	(18,829)	(38,565)	(38,565)
Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net of Tax	(34,971)	(35,805)	(71,623)	(34,971)	(71,623)	(71,623)	(37,579)	(71,623)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, Tax	0		0	0	0
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, Net of Tax	0		0	0	0
Other Comprehensive Income Defined benefit plan, amortization of gains, before tax	768		0	2,398	0
Other comprehensive Income, Defined Benefit Plan, Amortization of Gains, tax	269		0	839	0
Other Comprehensive Income, Defined benefit plan, amortization of gains, after tax	499		0	1,559	0
Accumulated Net Unrealized Investment Gain (Loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), before Tax	(22,480)	(5,696)	(18,446)	(22,480)	(18,446)	85,259	(45,072)	(420)
accumulated other comprehensive income, tax	(7,868)	(1,994)	(6,456)	(7,868)	(6,456)	29,841	(15,775)	(146)
Accumulated other comprehensive loss	$ (14,612)	$ (3,702)	$ (11,990)	$ (14,612)	$ (11,990)	$ 55,418	$ (29,297)	$ (274)