Pension and Postretirement Plans (Total Benefit/Cost) (Details 5) (USD $) In Thousands, unless otherwise specified	3 Months Ended							9 Months Ended		12 Months Ended
	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Dec. 31, 2011
Defined Benefit Plan Disclosure [Line Items]
Net Periodic Cost (Benefit)								$ 11,425	$ 9,980
Early retirement program expense								22,700	8,508
Total Cost (Benefit)	(2,733)	(2,638)	(2,729)	(631)	(1,134)	(3,368)	(3,475)	(8,100)	(7,977)	(8,608)	(23,219)
Amortization of prior service credit (cost)	(384)				(469)			(1,205)	(1,390)
Curtailment loss	0				0			(3,471)	0
Total Recognized in Other Comprehensive Income (Before Tax Effects)	(1,620)				(2,123)			(1,649)	(5,449)
Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	12,713				10,876			38,788	28,684
Interest cost	14,242				14,828			42,776	44,248
Expected return on assets	(26,817)				(23,779)			(78,606)	(72,301)
Amortization of prior service cost (credit)	908				919			2,726	2,775
Recognized actuarial loss (gain)	1,797				2,502			5,741	6,574
Net Periodic Cost (Benefit)	2,843				5,346			11,425	9,980
Early retirement program expense	0				7,486			22,700	8,508
Total Cost (Benefit)	2,843				12,832			34,125	18,488
Supplemental Executive Retirement Plan (SERP) [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	429				367			1,288	1,100
Interest cost	1,023				1,060			3,069	3,181
Amortization of prior service cost (credit)	14				14			41	41
Recognized actuarial loss (gain)	711				458			2,133	1,375
Total Cost (Benefit)	2,177				1,899			6,531	5,697
Other Postretirement Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	728				778			2,183	2,335
Interest cost	508				684			1,525	2,052
Amortization of prior service cost (credit)	(1,306)				(1,402)			(3,972)	(4,206)
Recognized actuarial loss (gain)	(504)				(370)			(1,549)	(1,110)
Net Periodic Cost (Benefit)	(574)				(310)			(1,813)	(929)
Settlement gain	0				0			(3,471)	0
Total Cost (Benefit)	$ (574)				$ (310)			$ (5,284)	$ (929)