Pension and Other Post-Retirement Benefit Plans (Unrecognized Net Periodic Benefit Expense) (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Unrecognized prior service cost	$ 0	$ 0
Unrecognized net actuarial loss	112,506	144,402
Accumulated other comprehensive loss	112,506	144,402
Post-Retirement Healthcare Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Unrecognized prior service cost	(51)	(153)
Unrecognized net actuarial loss	1,893	449
Accumulated other comprehensive loss	$ 1,842	$ 296