Pension Benefits and Other Postretirement Benefit Plans (Components of Net Periodic Benefit Cost) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 1,838	$ 1,990	$ 3,677	$ 4,008
Expected return on plan assets	(2,771)	(3,228)	(5,542)	(6,455)
Amortization of net loss	413	160	826	343
Settlement charge		(33)		77
Net periodic benefit cost (income)	(520)	(1,111)	(1,039)	(2,027)
Retirement Health and Life Insurance Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	150	159	300	319
Interest cost	75	84	150	167
Amortization of net loss		30		61
Net periodic benefit cost (income)	$ 225	$ 273	$ 450	$ 547