Employee Benefit Plans (Other Comprehensive Income) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Pension Plans
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Net actuarial (gain) loss experienced during the year	$ 28,748	$ 14,312	$ 4,332
Net actuarial loss recognized as expense	(4,908)	(3,755)	(3,290)
Prior service cost recognized as expense	(340)	(298)	(298)
Total recognized in other comprehensive income (loss)	23,500	10,259	744
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	313
Amortization of net actuarial loss	8,591
Postretirement Benefit Plans
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Net actuarial (gain) loss experienced during the year	(1,787)	2,111	(2,094)
Transition obligation recognized as expense	(294)	(286)	(280)
Total recognized in other comprehensive income (loss)	(2,081)	1,825	(2,374)
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	$ 264