Pension Benefits and Other Postretirement Benefit Plans (Components of Net Periodic Benefit Cost) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 1,839	$ 2,018
Expected return on plan assets	(2,771)	(3,227)
Amortization of net loss	413	183
Settlement charge		110
Net periodic benefit cost (income)	(519)	(916)
Retirement Health and Life Insurance Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	150	160
Interest cost	75	83
Amortization of prior service cost		0
Amortization of net loss		31
Net periodic benefit cost (income)	$ 225	$ 274