Pension Benefit and Retirement Health and Life Insurance Benefits (Assets Carried at Fair Value by Level) (Details) (Pension Benefits [Member], USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Defined Benefit Plan Disclosure [Line Items]
Pension assets	$ 171,218	$ 143,540	$ 120,565
Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension assets	119,277	98,269
Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension assets	38,584	29,869
Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension assets	13,357	15,402
Estimate of Fair Value [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension assets	171,218	143,540
Pooled separate accounts [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension assets	38,584	29,869
Pooled separate accounts [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension assets	0	0
Pooled separate accounts [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension assets	38,584	29,869
Pooled separate accounts [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension assets	0	0
Pooled separate accounts [Member] | Estimate of Fair Value [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension assets	38,584	29,869
Mutual funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension assets	119,277	98,269
Mutual funds [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension assets	119,277	98,269
Mutual funds [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension assets	0	0
Mutual funds [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension assets	0	0
Mutual funds [Member] | Estimate of Fair Value [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension assets	119,277	98,269
Guaranteed deposit account [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension assets	13,357	15,402
Guaranteed deposit account [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension assets	0	0
Guaranteed deposit account [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension assets	0	0
Guaranteed deposit account [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension assets	13,357	15,402
Guaranteed deposit account [Member] | Estimate of Fair Value [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension assets	$ 13,357	$ 15,402