Retirement Plan (Narrative) (Details) (USD $)	12 Months Ended			3 Months Ended			12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 Defined Benefit Pension Plans	Jun. 30, 2012 Defined Benefit Pension Plans	Dec. 31, 2011 Defined Benefit Pension Plans	Dec. 31, 2012 Overall Rate Using Financial Simulation Model Of Asset Returns	Dec. 31, 2012 Retirement Restoration Plan	Dec. 31, 2011 Retirement Restoration Plan	Dec. 31, 2010 Retirement Restoration Plan	Dec. 31, 2012 401(K) Plans	Dec. 31, 2011 401(K) Plans	Dec. 31, 2010 401(K) Plans	Dec. 31, 2012 Post-retirement Healthcare Plans	Dec. 31, 2012 Other Postretirement Benefit Plans, Defined Benefit	Dec. 31, 2011 Other Postretirement Benefit Plans, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation, adjustment	$ (53,450,000)	$ 3,515,000	$ 238,000		$ 7,100,000
Pension expense					700,000			300,000	600,000	600,000	16,000,000	9,700,000	5,500,000
Pension expense, charges on plan termination, before tax	37,600,000
Pension expense, charges on plan termination, after tax	23,000,000
Accrued pension liability				(17,728,000)		(31,980,000)									(26,797,000)	(77,303,000)
Accumulated benefit obligation				95,500,000		86,100,000									26,800,000	77,300,000
Expected long-term rate of return on assets	6.50%	8.00%	8.50%				0.25%
Defined benefit plan, period for expected future benefit payments on frozen plan	3 years
Amendments				15,600,000											49,399,000	5,387,000
Accrued liability								7,400,000	6,700,000
Projected benefit obligations under this plan								7,400,000
2013								700,000							9,700,000
2014								2,200,000							1,400,000
2015								500,000							1,300,000
2016								500,000							1,300,000
2017								1,500,000							1,300,000
2018-2022								1,400,000							7,500,000
Post-retirement Healthcare Plans, elimination of benefits, age														65 years
Post-retirement Healthcare Plans, elimination of early retirement benefits, age														62 years
Post-retirement Healthcare Plans, requirement for cash payment in lieu of benefits, age														65 years
Defined Benefit Plan, Estimated Future Employer Contributions in Next Fiscal Year														$ 8,300,000