Pension Benefit and Retirement Health and Life Insurance Benefits (Amounts Recognized in Balance Sheet) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan, Amounts Recognized in Balance Sheet [Abstract]
Noncurrent assets	$ 403	$ 2,982
Pension Benefits [Member]
Defined Benefit Plan, Amounts Recognized in Balance Sheet [Abstract]
Noncurrent assets	404	2,983
Current liabilities	(34)	(654)
Noncurrent liabilities	(17,652)	(5,436)
Net amount recognized at end of year	(17,282)	(3,107)
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax [Abstract]
Net actuarial loss	62,053
Prior service cost	0
Net amount recognized at end of year	62,053
Retirement Health and Life Insurance Benefits [Member]
Defined Benefit Plan, Amounts Recognized in Balance Sheet [Abstract]
Noncurrent assets	0	0
Current liabilities	(1,071)	(1,175)
Noncurrent liabilities	(8,768)	(9,649)
Net amount recognized at end of year	(9,839)	(10,824)
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax [Abstract]
Net actuarial loss	707
Prior service cost	0
Net amount recognized at end of year	$ 707