Defined Benefit Pension and Other Post Retirement Plans (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Projected Benefit Obligation
Beginning Balance	$ 271,134	$ 572,097
Pension settlement		(339,799)	(339,799)
Actuarial loss	24,330	34,784
Interest cost	12,498	13,265	32,829
Benefits paid	(9,791)	(9,213)
Ending Balance	298,171	271,134	572,097
Fair Value of Plan Assets
Beginning Balance	158,823	380,010
Pension settlement		(238,833)	(238,833)
Actual return (loss) on plan assets	23,323	(298)
Employer contributions	19,226	27,157
Benefits paid	(9,791)	(9,213)
Ending Balance	191,581	158,823	380,010
Defined Benefit Plan, Funded Status of Plan, Total	(106,590)	(112,311)
Accumulated Benefit Obligation	$ 298,171	$ 271,134