Pension and Postretirement Benefits (Details 4) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011
Summary of accumulated other comprehensive losses recognized in net periodic benefit
Amortization of prior service cost	$ (947)
Amortization of net actuarial loss	8,991
Total	8,044
Pension Plan [Member]
Summary of accumulated other comprehensive losses recognized in net periodic benefit
Amortization of prior service cost	(801)
Amortization of net actuarial loss	8,484
Total	7,683
Postretirement Plan [Member]
Summary of accumulated other comprehensive losses recognized in net periodic benefit
Amortization of prior service cost	(146)
Amortization of net actuarial loss	507
Total	$ 361