Retirement Plan (Net Periodic Pension Expense) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Jun. 30, 2012	Sep. 30, 2012	Sep. 30, 2011
Defined Benefit Retirement Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost - benefit earned during the period	$ 0	$ 1,268		$ 679	$ 3,803
Interest cost on projected benefit obligations	955	1,281		3,007	3,844
Expected return on plan assets	(950)	(1,244)		(2,849)	(3,923)
Amortization of prior service cost	0	97		67	293
Amortization of net loss	415	529		1,518	1,594
Estimated effect of curtailment	0	798	7,100	899	798
Net periodic pension expense	420	2,729		3,321	6,409
Other Post-Retirement Healthcare and Other Benefits Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost - benefit earned during the period	475			1,425
Interest cost on projected benefit obligations	875			2,625
Amortization of prior service cost	(550)			(1,650)
Amortization of net loss	75			225
Net periodic pension expense	$ 875			$ 2,625