Pension and Postretirement Plans (Total Benefit/Cost) (Details 1) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Defined Benefit Plan Disclosure [Line Items]
Net Periodic Cost (Benefit)	$ 4,963	$ 4,317	$ 10,184	$ 9,257
Defined Benefit Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	4,963	4,317	10,184	9,257
Interest cost	11,743	11,844	23,335	23,099
Expected return on assets	(30,285)	(32,796)	(61,123)	(65,282)
Amortization of prior service cost (credit)	825	36	1,234	78
Recognized actuarial loss (gain)	37	(2,974)	0	(4,020)
Net Periodic Cost (Benefit)	(12,717)	(19,573)	(26,370)	(36,868)
Curtailment gain	0	0	0	(806)
Special separation benefit expense	6,607	0	6,607	0
Net Periodic Cost (Benefit)	(6,110)	(19,573)	(19,763)	(37,674)
Supplemental Executive Retirement Plan (SERP) [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	215	204	429	409
Interest cost	1,079	966	2,157	1,932
Amortization of prior service cost (credit)	84	78	169	156
Recognized actuarial loss (gain)	578	601	1,157	1,202
Net Periodic Cost (Benefit)	1,956	1,849	3,912	3,699
Other Postretirement Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	268	0	536
Interest cost	72	169	144	339
Amortization of prior service cost (credit)	(1,840)	(44)	(3,681)	(88)
Recognized actuarial loss (gain)	(1,090)	(921)	(2,180)	(1,843)
Net Periodic Cost (Benefit)	$ (2,858)	$ (528)	$ (5,717)	$ (1,056)