Pension and Other Post-Retirement Benefits (Components of Pension Expense and Other Post-Retirement Benefit Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 0	$ 54	$ 0
Interest cost	18,507	21,286	20,518
Expected return on plan assets	(23,542)	(25,046)	(24,157)
Amortization of prior service cost	0	0	0
Amortization of actuarial loss	13,174	11,186	7,378
Total	8,139	7,480	3,739
Other Post-Retirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	0	0	0
Interest cost	35	46	49
Expected return on plan assets	0	0	0
Amortization of prior service cost	(103)	(103)	(103)
Amortization of actuarial loss	47	37	34
Total	$ (21)	$ (20)	$ (20)