Pension and Postretirement Plans (Accumulated Other Comprehensive Income) (Details 7) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Net amount	$ (170,830)	$ (261,029)
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Unrecognized actuarial (gain) loss	(285,304)	(451,076)
Unrecognized prior service cost	365	662
Gross amount	(284,939)	(450,414)
Deferred tax liability (asset)	113,976	180,166
Net amount	(170,963)	(270,248)
Supplemental Executive Retirement Plan (SERP) [Member]
Defined Benefit Plan Disclosure [Line Items]
Unrecognized actuarial (gain) loss	24,958	26,497
Unrecognized prior service cost	775	1,232
Gross amount	25,733	27,729
Deferred tax liability (asset)	(10,293)	(11,091)
Net amount	15,440	16,638
Other Postretirement Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Unrecognized actuarial (gain) loss	(25,186)	(11,704)
Unrecognized prior service cost	(326)	(661)
Gross amount	(25,512)	(12,365)
Deferred tax liability (asset)	10,205	4,946
Net amount	$ (15,307)	$ (7,419)