Retirement Plans Components of Net Periodic Benefit Cost (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Retirement Plans (Textuals) [Abstract]
Retirement eligible age for participation	55
Years of service for pension plan eligibility	5
Pension Plans, Defined Benefit [Member]
Net period benefit cost for the pension and postretirement plans
Service cost	$ 2,975	$ 2,975	$ 12,078
Interest cost	1,790	1,548	6,237
Expected return on plan assets	(4,855)	(4,305)	(17,647)
Amortization of prior service cost	15	17	72
Amortization of actuarial (gain) loss	325	1,073	4,344
Total net periodic benefit cost	250	1,308	5,084
Other Postretirement Benefit Plans, Defined Benefit [Member]
Net period benefit cost for the pension and postretirement plans
Interest cost	39	40	142
Amortization of actuarial (gain) loss	(9)	0	0
Total net periodic benefit cost	$ 30	$ 40	$ 142