Pension and Postretirement Plans (Accumulated Other Comprehensive Income) (Details 7) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Net amount	$ (232,836)	$ (334,536)
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Unrecognized actuarial (gain) loss	(313,809)	(461,779)
Unrecognized prior service cost	7,273	270
Gross amount	(306,536)	(461,509)
Deferred tax liability (asset)	82,765	124,607
Net amount	(223,771)	(336,902)
Supplemental Executive Retirement Plan (SERP) [Member]
Defined Benefit Plan Disclosure [Line Items]
Unrecognized actuarial (gain) loss	17,270	27,225
Unrecognized prior service cost	1,037	320
Gross amount	18,307	27,545
Deferred tax liability (asset)	(4,943)	(7,437)
Net amount	13,364	20,108
Other Postretirement Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Unrecognized actuarial (gain) loss	(22,861)	(24,125)
Unrecognized prior service cost	(7,863)	(178)
Gross amount	(30,724)	(24,303)
Deferred tax liability (asset)	8,295	6,561
Net amount	$ (22,429)	$ (17,742)