Employee Benefit Plans Net Periodic Benefit Cost (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Pension Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 8,452	$ 8,407	$ 6,782
Interest cost	16,682	17,284	18,087
Expected return on plan assets	(25,302)	(25,477)	(25,819)
Amortization of prior service cost	1,296	1,308	1,359
Amortization of losses	20,097	17,578	10,372
Amortization of negative plan amendment	0	0	0
Curtailment expense	60	0	0
Settlement expense	817	0	0
Net periodic benefit cost	22,102	19,100	10,781
Other Postretirement Benefit Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	1,056	918	673
Interest cost	937	956	972
Expected return on plan assets	0	0	0
Amortization of prior service cost	66	80	69
Amortization of losses	675	582	570
Amortization of negative plan amendment	(105)	(55)	0
Curtailment expense	0	0	0
Settlement expense	0	0	0
Net periodic benefit cost	$ 2,629	$ 2,481	$ 2,284