Employee Benefit Plans (Other Comprehensive Income) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Pension Plans
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Net actuarial (gain) loss experienced during the year	$ 14,312	$ 4,332	$ 5,683
Net actuarial loss recognized as expense	(3,755)	(3,290)	(2,559)
Prior service cost recognized as expense	(298)	(298)	(298)
Total recognized in other comprehensive income	10,259	744	2,826
Pension and Other Postretirement Benefit Plans, Amounts that Will be Amortized from Accumulated Other Comprehensive Income (Loss) in Next Fiscal Year [Abstract]
Amortization of prior service cost	341
Amortization of net actuarial gain	4,721
Postretirement Benefit Plans
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Net actuarial (gain) loss experienced during the year	2,111	(2,094)	(1,363)
Net actuarial loss recognized as expense	0	0	(46)
Amortization of transition asset	(286)	(280)	(280)
Total recognized in other comprehensive income	1,825	(2,374)	(1,689)
Pension and Other Postretirement Benefit Plans, Amounts that Will be Amortized from Accumulated Other Comprehensive Income (Loss) in Next Fiscal Year [Abstract]
Amortization of transition obligation	286
Amortization of net actuarial gain	$ 0