Employee Benefit Plans Employee Benefit Plans (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Defined Benefit Pension Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service Cost	$ 1,608	$ 1,431	$ 4,824	$ 4,291
Interest Cost	3,825	3,688	11,475	11,062
Expected Return on Plan Assets	(4,654)	(4,084)	(13,962)	(12,252)
Prior Service Cost (Benefit)	16	22	48	66
Net Loss (Gain)	3,062	2,408	9,186	7,224
Net Periodic Benefit Cost	3,857	3,465	11,571	10,391
Pension and Other Postretirement Benefit Contributions [Abstract]
Estimated Future Employer Contributions In Current Fiscal Year			0
Estimated Future Employer Contributions in Next Fiscal Year			12,500
Non-pension Defined Benefit Postretirement Healthcare Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service Cost	419	402	1,257	1,206
Interest Cost	417	523	1,251	1,569
Expected Return on Plan Assets	(20)	(19)	(60)	(57)
Prior Service Cost (Benefit)	(125)	(125)	(375)	(375)
Net Loss (Gain)	121	222	363	666
Net Periodic Benefit Cost	812	1,003	2,436	3,009
Pension and Other Postretirement Benefit Contributions [Abstract]
Estimated Future Employer Contributions In Current Fiscal Year			784
Estimated Future Employer Contributions in Next Fiscal Year			3,350
Supplemenatal Non-qualified Defined Benefit Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service Cost	348	243	1,044	735
Interest Cost	332	331	996	993
Prior Service Cost (Benefit)	1	1	3	3
Net Loss (Gain)	198	202	594	606
Net Periodic Benefit Cost	879	777	2,637	2,337
Pension and Other Postretirement Benefit Contributions [Abstract]
Estimated Future Employer Contributions In Current Fiscal Year			322
Estimated Future Employer Contributions in Next Fiscal Year			1,463
Scenario, Actual [Member] | Defined Benefit Pension Plan [Member]
Pension and Other Postretirement Benefit Contributions [Abstract]
Contributions Made by Employer	12,500		12,500
Scenario, Actual [Member] | Non-pension Defined Benefit Postretirement Healthcare Plans [Member]
Pension and Other Postretirement Benefit Contributions [Abstract]
Contributions Made by Employer	784		2,352
Scenario, Actual [Member] | Supplemenatal Non-qualified Defined Benefit Plans [Member]
Pension and Other Postretirement Benefit Contributions [Abstract]
Contributions Made by Employer	$ 322		$ 966