Pension and Postretirement Plans (Total Benefit/Cost) (Details 5) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Early retirement programs and special separation benefit expense		$ 0	$ 4,606	$ 8,374
Total Cost (Benefit) for the Year		(67,097)	(60,557)	(64,780)
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Current year actuarial gain (loss)		133,915	211,054	149,482
Current year prior service cost		0	0	1,600
Amortization of prior service credit (cost)		(419)	(275)	407
Recognized net actuarial gain (loss)		(1,157)	9,906	29,412
Curtailments and settlements		17,993	(51)	(8)
Total Recognized in Other Comprehensive Income (Before Tax Effects)		150,332	219,800	180,893
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		20,461	26,294	27,792
Interest cost		51,608	52,613	51,825
Expected return on assets		(121,470)	(130,571)	(120,472)
Amortization of prior service cost (credit)		297	320	329
Recognized actuarial loss (gain)		0	(11,925)	(28,880)
Net Periodic Cost (Benefit) for the Year		(49,104)	(63,269)	(69,406)
Curtailment		0	(3,267)	0
Settlement	$ 18,000	(17,993)	0	0
Early retirement programs and special separation benefit expense		0	4,606	8,374
Total Cost (Benefit) for the Year		(67,097)	(61,930)	(61,032)
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Current year actuarial gain (loss)		147,779	222,894	125,866
Amortization of prior service credit (cost)		(297)	(320)	(329)
Recognized net actuarial gain (loss)		0	11,925	28,880
Curtailments and settlements		17,993	(51)	(368)
Total Recognized in Other Comprehensive Income (Before Tax Effects)		165,475	234,448	154,049
Total Recognized in Total (Benefit) Cost and Other Comprehensive Income (Before Tax Effects)		98,378	172,518	93,017
Supplemental Executive Retirement Plan (SERP) [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		985	1,946	1,493
Interest cost		4,384	4,550	4,397
Amortization of prior service cost (credit)		457	457	47
Recognized actuarial loss (gain)		2,659	3,015	1,544
Net Periodic Cost (Benefit) for the Year		8,485	9,968	7,481
Early retirement programs and special separation benefit expense		0	0	2,422
Total Cost (Benefit) for the Year		8,485	9,968	9,903
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Current year actuarial gain (loss)		1,120	(6,544)	19,168
Current year prior service cost		0	0	1,600
Amortization of prior service credit (cost)		(457)	(457)	(47)
Recognized net actuarial gain (loss)		(2,659)	(3,015)	(1,544)
Curtailments and settlements		0	(834)	0
Total Recognized in Other Comprehensive Income (Before Tax Effects)		(1,996)	(10,850)	19,177
Total Recognized in Total (Benefit) Cost and Other Comprehensive Income (Before Tax Effects)		6,489	(882)	29,080
Other Postretirement Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		1,386	1,331	1,500
Interest cost		1,230	1,299	1,448
Amortization of prior service cost (credit)		(335)	(502)	(783)
Recognized actuarial loss (gain)		(1,502)	(996)	(2,076)
Net Periodic Cost (Benefit) for the Year		779	1,132	89
Curtailment		0	0	(1,292)
Total Cost (Benefit) for the Year		779	1,132	(1,203)
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Current year actuarial gain (loss)		(14,984)	(5,296)	4,448
Amortization of prior service credit (cost)		335	502	783
Recognized net actuarial gain (loss)		1,502	996	2,076
Curtailments and settlements		0	0	360
Total Recognized in Other Comprehensive Income (Before Tax Effects)		(13,147)	(3,798)	7,667
Total Recognized in Total (Benefit) Cost and Other Comprehensive Income (Before Tax Effects)		$ (12,368)	$ (2,666)	$ 6,464