Employee Benefit Plans Net Periodic Benefit Cost (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Pension Benefits [Member]
Components of Net Periodic Benefit Cost (Income) [Abstract]
Service cost	$ 2,999	$ 3,439
Interest cost	6,545	5,624
Expected return on plan assets	(7,377)	(8,125)
Amortization of prior service cost	62	62
Recognized actuarial loss	557	2,752
Net Periodic Benefit Cost (Income)	2,786	3,752
Other Postretirement Benefits [Member]
Components of Net Periodic Benefit Cost (Income) [Abstract]
Service cost	126	156
Interest cost	211	217
Expected return on plan assets	(245)	(254)
Amortization of prior service cost	(500)	(500)
Recognized actuarial loss	77	225
Net Periodic Benefit Cost (Income)	$ (331)	$ (156)