Pension Plans and Other Postretirement Benefits (Details 2) (USD $) In Thousands, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2012	Dec. 31, 2011
Defined Benefit Plan [Member]
Contributions made and expected full year contributions for the Company's plans
Minimum funding requirement for 2012	$ 1,000
Defined benefit plan Contributions	373
Expected contributions (approximations)
Expected contributions (approximations) for the full fiscal year, as of the time of this form 10-Q	2,300
Expected contributions (approximations) for the full fiscal year, as of the time of the prior year-end 10-K		2,300
Supplemental Defined Benefit Plans [Member]
Contributions made and expected full year contributions for the Company's plans
Defined benefit plan Contributions	657
Expected contributions (approximations)
Expected contributions (approximations) for the full fiscal year, as of the time of this form 10-Q	1,300
Expected contributions (approximations) for the full fiscal year, as of the time of the prior year-end 10-K		1,300
Postretirement Benefit Plans [Member]
Contributions made and expected full year contributions for the Company's plans
Defined benefit plan Contributions	270
Expected contributions (approximations)
Expected contributions (approximations) for the full fiscal year, as of the time of this form 10-Q	519
Expected contributions (approximations) for the full fiscal year, as of the time of the prior year-end 10-K		$ 519