Pension and Postretirement Benefits (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2012
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Service Cost	$ 605	$ 606	$ 1,843	$ 1,770
Defined Benefit Plan, Interest Cost	1,442	1,579	4,369	4,657
Defined Benefit Plan, Expected Return on Plan Assets	(1,358)	(1,440)	(4,101)	(4,313)
Defined Benefit Plan, Other Costs	715	529	2,151	1,450
Defined Benefit Plan, Net Periodic Benefit Cost	1,404	1,274	4,262	3,564
Defined Benefit Plan, Estimated Future Employer Contributions in Current Fiscal Year					6,826
Defined Benefit Plan, Contributions by Employer			5,895
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Service Cost	5	4	14	14
Defined Benefit Plan, Interest Cost	71	88	213	266
Defined Benefit Plan, Expected Return on Plan Assets	0	0	0	0
Defined Benefit Plan, Other Costs	31	33	92	95
Defined Benefit Plan, Net Periodic Benefit Cost	107	125	319	375
Defined Benefit Plan, Estimated Future Employer Contributions in Current Fiscal Year					747
Defined Benefit Plan, Contributions by Employer			$ 604