Benefit Plans Benefit Plans - Future Benefit Payments (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013
Pension Benefits [Member]
Defined Benefit Plan, Amount to be Amortized from Accumulated Other Comprehensive Income (Loss) Next Fiscal Year [Abstract]
Amount of net prior service cost (credit)	$ (156)
Amount of net loss	3,131
2014	28,253
2015	27,439
2016	27,613
2017	27,838
2018	28,238
2019-2023	146,370
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan, Amount to be Amortized from Accumulated Other Comprehensive Income (Loss) Next Fiscal Year [Abstract]
Amount of net prior service cost (credit)	(226)
Amount of net loss	202
Other Benefits before Medicare Part D
Defined Benefit Plan, Amount to be Amortized from Accumulated Other Comprehensive Income (Loss) Next Fiscal Year [Abstract]
2014	1,695
2015	1,632
2016	1,574
2017	1,512
2018	1,433
2019-2023	5,905
Other Postretirement Benefit Plans, After Medicare Part D Subsidy, Defined Benefit [Member]
Defined Benefit Plan, Amount to be Amortized from Accumulated Other Comprehensive Income (Loss) Next Fiscal Year [Abstract]
2014	1,519
2015	1,461
2016	1,410
2017	1,356
2018	1,286
2019-2023	$ 5,311