Pensions and Other Benefits (Details) (Defined benefit pension plan and combined supplemental executive retirement plans ("SERPs"') [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Defined benefit pension plan and combined supplemental executive retirement plans ("SERPs"') [Member]
Net periodic benefit expense
Interest cost	$ 2,639	$ 2,841	$ 5,278	$ 5,682
Expected return on plan assets	(1,968)	(2,056)	(3,937)	(4,111)
Amortization of prior service cost	7	7	14	14
Recognized net actuarial loss	1,470	1,572	2,940	3,144
Net periodic benefit expense	2,148	2,364	4,295	4,729
Summary of the net actuarial loss and prior service costs
Net actuarial loss	1,470	1,572	2,940	3,144
Tax benefit on net actuarial loss	(559)	(597)	(1,117)	(1,195)
Prior service costs	7	7	14	14
Tax (benefit) expense on prior service costs	(3)	(2)	(6)	(5)
Net amortization from accumulated other comprehensive income	$ 915	$ 980	$ 1,831	$ 1,958