Employee Benefit Plans Employee Benefit Plans and Components of Net Periodic Postretirement Benefit Cost (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Cash contribution to pension plan	$ 0
Anticipated cash contribution to pension plan	0
Pension and Other Postretirement Plans, Defined Benefit
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	213	192
Interest cost	1,619	1,750
Expected return on assets	(2,320)	(2,464)
Amortization of prior service cost	81	81
Amortization of actuarial loss	485	149
Net periodic pension and postretirement benefit cost (credit)	$ 78	$ (292)