Employee Benefit Plans Employee Benefit Plans and Components of Net Periodic Postretirement Benefit Cost (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Contributions paid	$ 0	$ 0	$ 0	$ 0
Anticipated cash contributions to pension plan in remaining fiscal year	0		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	426	384
Interest cost	1,619	1,750	3,238	3,500
Expected return on assets	(2,320)	(2,464)	(4,640)	(4,928)
Amortization of prior service cost	81	81	162	162
Amortization of actuarial loss	485	149	970	298
Net periodic pension and postretirement benefit cost (credit)	$ 78	$ (292)	$ 156	$ (584)