Pension and Other Postretirement Benefits Net Periodic Benefit Cost (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Pension Plans, Defined Benefit
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 5,597	$ 6,525
Interest cost	6,799	5,975
Expected return on plan assets	(6,675)	(5,975)
Amortization of net actuarial loss	4,534	6,325
Amortization of prior service cost (gain)	246	350
Settlement loss	789	0
Net periodic benefit cost	11,290	13,200
Other Postretirement Benefit Plans, Defined Benefit
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	625	675
Interest cost	825	725
Expected return on plan assets	0	0
Amortization of net actuarial loss	275	475
Amortization of prior service cost (gain)	(550)	(550)
Settlement loss	0	0
Net periodic benefit cost	$ 1,175	$ 1,325