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		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Other comprehensive income, net of tax	$ 1,511	$ 919	$ 4,471	$ 2,759
Other Postretirement Employee Benefits [Member]
Other comprehensive income, net of tax	(948)	(697)	(2,906)	(2,090)
Pension Plans [Member]
Other comprehensive income, net of tax	$ 2,459	$ 1,616	$ 7,377	$ 4,849