Employee Benefit Plans Net Periodic Benefit Cost (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Pension Benefits [Member]
Components of Net Periodic Benefit Cost (Income) [Abstract]
Service cost	$ 2,708	$ 3,367	$ 8,123	$ 10,100
Interest cost	6,536	5,680	19,610	17,040
Expected return on plan assets	(7,377)	(8,123)	(22,130)	(24,369)
Amortization of prior service cost	62	62	185	185
Recognized actuarial loss	530	2,911	1,589	8,735
Net Periodic Benefit Cost (Income)	2,459	3,897	7,377	11,691
Other Postretirement Benefits [Member]
Components of Net Periodic Benefit Cost (Income) [Abstract]
Service cost	116	135	349	406
Interest cost	214	219	644	658
Expected return on plan assets	(245)	(254)	(736)	(764)
Amortization of prior service cost	(500)	(500)	(1,499)	(1,499)
Recognized actuarial loss	87	242	261	728
Net Periodic Benefit Cost (Income)	$ (328)	$ (158)	$ (981)	$ (471)