Pension and Postretirement Benefits (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2012
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Service Cost	$ 614	$ 593	$ 1,238	$ 1,164
Defined Benefit Plan, Interest Cost	1,457	1,555	2,927	3,077
Defined Benefit Plan, Expected Return on Plan Assets	(1,368)	(1,449)	(2,743)	(2,873)
Defined Benefit Plan, Other Costs	717	461	1,436	921
Defined Benefit Plan, Net Periodic Benefit Cost	1,420	1,160	2,858	2,289
Defined Benefit Plan, Estimated Future Employer Contributions in Current Fiscal Year					6,826
Defined Benefit Plan, Contributions by Employer			4,652
Other Postretirement Benefit Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Service Cost	5	5	9	10
Defined Benefit Plan, Interest Cost	71	89	142	178
Defined Benefit Plan, Expected Return on Plan Assets	0	0	0	0
Defined Benefit Plan, Other Costs	30	31	61	62
Defined Benefit Plan, Net Periodic Benefit Cost	106	125	212	250
Defined Benefit Plan, Estimated Future Employer Contributions in Current Fiscal Year					747
Defined Benefit Plan, Contributions by Employer			$ 467