Pension Benefit and Other Postretirement Benefit Plans (Components of Net Periodic Benefit Cost) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost		$ 956		$ 2,210
Interest cost	1,990	1,954	4,008	4,015
Expected return on plan assets	(3,228)	(2,731)	(6,455)	(5,447)
Amortization of prior service cost		31		124
Amortization of net loss	160	1,049	343	2,525
Special termination benefit
Settlement charge	(33)		77
Curtailment charge		1,537		1,537
Net periodic benefit cost (income)	(1,111)	2,796	(2,027)	4,964
Retirement Health and Life Insurance Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	159	170	319	341
Interest cost	84	71	167	141
Expected return on plan assets
Amortization of prior service cost		(57)		(115)
Amortization of net loss	30	82	61	165
Special termination benefit		0
Settlement charge
Curtailment charge
Net periodic benefit cost (income)	$ 273	$ 266	$ 547	$ 532