Pension and Postretirement Plans (Total Benefit/Cost) (Details 5) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Dec. 31, 2018	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Early retirement programs and special separation benefit expense			$ 0	$ 1,825	$ 0
Total Cost (Benefit) for the Year			18,221	18,687	20,461
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Current year actuarial gain (loss)			101,013	(179,674)	133,915
Current year prior service cost			(4,262)	75	0
Amortization of prior service credit (cost)			947	(477)	(419)
Recognized net actuarial gain (loss)			11,349	6,527	(1,157)
Curtailments and settlements			30,267	0	17,993
Total Recognized in Other Comprehensive Income (Before Tax Effects)			139,314	(173,549)	150,332
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost			18,221	18,687	20,461
Interest cost			46,787	47,925	51,608
Expected return on assets			(129,220)	(121,411)	(121,470)
Amortization of prior service cost (credit)			150	170	297
Recognized actuarial loss (gain)			(9,969)	(4,410)	0
Net Periodic Cost (Benefit) for the Year			(74,031)	(59,039)	(49,104)
Curtailment			(806)	0	0
Settlement	$ (26,900)	$ (18,000)	(26,917)	0	(17,993)
Early retirement programs and special separation benefit expense			0	1,825	0
Total Cost (Benefit) for the Year			(101,754)	(57,214)	(67,097)
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Current year actuarial gain (loss)			111,084	(180,885)	147,779
Current year prior service cost			7,183	75	0
Amortization of prior service credit (cost)			(150)	(170)	(297)
Recognized net actuarial gain (loss)			9,969	4,410	0
Curtailments and settlements			26,887	0	17,993
Total Recognized in Other Comprehensive Income (Before Tax Effects)			154,973	(176,570)	165,475
Total Recognized in Total (Benefit) Cost and Other Comprehensive Income (Before Tax Effects)			53,219	(233,784)	98,378
Supplemental Executive Retirement Plan (SERP) [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost			819	858	985
Interest cost			3,865	4,233	4,384
Amortization of prior service cost (credit)			311	455	457
Recognized actuarial loss (gain)			2,403	1,774	2,659
Total Cost (Benefit) for the Year			7,398	7,320	8,485
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Current year actuarial gain (loss)			(7,552)	4,041	1,120
Current year prior service cost			1,028	0	0
Amortization of prior service credit (cost)			(311)	(455)	(457)
Recognized net actuarial gain (loss)			(2,403)	(1,774)	(2,659)
Total Recognized in Other Comprehensive Income (Before Tax Effects)			(9,238)	1,812	(1,996)
Total Recognized in Total (Benefit) Cost and Other Comprehensive Income (Before Tax Effects)			(1,840)	9,132	6,489
Other Postretirement Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost			892	1,028	1,386
Interest cost			620	779	1,230
Amortization of prior service cost (credit)			(1,408)	(148)	(335)
Recognized actuarial loss (gain)			(3,783)	(3,891)	(1,502)
Net Periodic Cost (Benefit) for the Year			(3,679)	(2,232)	779
Curtailment			(3,380)	0	0
Total Cost (Benefit) for the Year			(7,059)	(2,232)	779
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Current year actuarial gain (loss)			(2,519)	(2,830)	(14,984)
Current year prior service cost			(12,473)	0	0
Amortization of prior service credit (cost)			1,408	148	335
Recognized net actuarial gain (loss)			3,783	3,891	1,502
Curtailments and settlements			3,380	0	0
Total Recognized in Other Comprehensive Income (Before Tax Effects)			(6,421)	1,209	(13,147)
Total Recognized in Total (Benefit) Cost and Other Comprehensive Income (Before Tax Effects)			$ (13,480)	$ (1,023)	$ (12,368)