Pension Plans and Other Postretirement Employee Benefits Pension Plans and Other Postretirement Employee Benefits (Components of Other Comprehensive Income, Net of Tax) (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
Other comprehensive income, net of tax	$ 1,375	$ 843	$ 2,960	$ 1,840
Other Postretirement Employee Benefits [Member]
Other comprehensive income, net of tax	(1,167)	(753)	(1,959)	(1,393)
Pension Plans [Member]
Other comprehensive income, net of tax	$ 2,542	$ 1,596	$ 4,919	$ 3,233