Pension and Other Postretirement Benefits Benefit Obligation (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Award vesting period	3 years
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Health care cost trend rate	7.50%	8.00%
Ultimate health care cost trend rate	5.00%	5.00%
Pension Benefits
Defined Benefit Plan Funded Status of Plan [Abstract]
Projected benefit obligation	$ (558,650)	$ (598,917)
Fair value of plan assets	423,167	430,894
Funded status	(135,483)	(168,023)
Accumulated benefit obligation	476,807	499,499
Pension and Other Postretirement Defined Benefit Plans, Liabilities [Abstract]
Current accrued benefit cost	(2,900)	(800)
Non-current accrued benefit cost	(132,583)	(167,223)
Net amount recognized	(135,483)	(168,023)
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), after Tax [Abstract]
Net actuarial loss	138,186	164,064
Prior service cost (gain)	1,575	2,415
Accumulated other comprehensive loss	139,761	166,479
Pension and Other Postretirement Benefit Plans, Amounts that Will be Amortized from Accumulated Other Comprehensive Income (Loss) in Next Fiscal Year [Abstract]
Net actuarial loss	11,120
Prior service cost (gain)	611
Accumulated other comprehensive loss	11,731
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Discount rate	4.87%	3.95%
Rate of compensation increase	4.25%	4.25%
Postretirement Benefits
Defined Benefit Plan Funded Status of Plan [Abstract]
Projected benefit obligation	(76,134)	(83,836)
Fair value of plan assets	0	0
Funded status	(76,134)	(83,836)
Pension and Other Postretirement Defined Benefit Plans, Liabilities [Abstract]
Current accrued benefit cost	(8,600)	(6,800)
Non-current accrued benefit cost	(67,534)	(77,036)
Net amount recognized	(76,134)	(83,836)
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), after Tax [Abstract]
Net actuarial loss	13,780	20,233
Prior service cost (gain)	(6,525)	(7,858)
Accumulated other comprehensive loss	7,255	12,375
Pension and Other Postretirement Benefit Plans, Amounts that Will be Amortized from Accumulated Other Comprehensive Income (Loss) in Next Fiscal Year [Abstract]
Net actuarial loss	672
Prior service cost (gain)	(1,344)
Accumulated other comprehensive loss	$ (672)
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Discount rate	4.34%	3.51%
Rate of compensation increase	0.00%	0.00%
Health care cost trend rate	7.50%
January 1, 2019 | Postretirement Benefits
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Ultimate health care cost trend rate	5.00%