Pension Benefits and Other Postretirement Benefit Plans (Components of Net Periodic Benefit Cost) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 1,846	$ 2,004	$ 5,523	$ 6,012
Expected return on plan assets	(2,772)	(3,227)	(8,314)	(9,682)
Amortization of net loss	432	172	1,258	515
Settlement charge				77
Net periodic benefit cost (income)	(494)	(1,051)	(1,533)	(3,078)
Retirement Health and Life Insurance Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	150	160	450	479
Interest cost	75	83	225	250
Amortization of net loss		31		92
Net periodic benefit cost (income)	$ 225	$ 274	$ 675	$ 821