Retirement and Postretirement Benefits Other than Pension Plans (Details) (Pension Plans, Defined Benefit [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
Pension Plans, Defined Benefit [Member]
Net periodic benefit expense components
Interest cost	$ 1,087	$ 1,209	$ 2,174	$ 2,417
Expected return on plan assets	(1,173)	(1,334)	(2,346)	(2,667)
Amortization of net actuarial loss	1,170	619	2,340	1,238
Total net periodic pension expense	$ 1,084	$ 494	$ 2,168	$ 988