Pension Benefit and Retirement Health and Life Insurance Benefits (Amounts Recognized in Balance Sheet) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Pension Benefits [Member]
Defined Benefit Plan, Amounts Recognized in Balance Sheet [Abstract]
Noncurrent assets	$ 0	$ 0
Current liabilities	(362)	(4,279)
Noncurrent liabilities	(65,942)	(68,871)
Net amount recognized at end of year	(66,304)	(73,150)
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax [Abstract]
Net actuarial loss	87,911
Prior service cost	1,660
Net amount recognized at end of year	89,571
Retirement Health and Life Insurance Benefits [Member]
Defined Benefit Plan, Amounts Recognized in Balance Sheet [Abstract]
Noncurrent assets	0	0
Current liabilities	(1,237)	(1,009)
Noncurrent liabilities	(10,654)	(9,486)
Net amount recognized at end of year	(11,891)	(10,495)
Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), before Tax [Abstract]
Net actuarial loss	3,187
Prior service cost	(229)
Net amount recognized at end of year	$ 2,958