Comprehensive Income (Details) (USD $)	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Comprehensive Income
Net income	$ 40,616,000	$ 81,813,000
Change in pension and other postretirement benefit plans, net of deferred taxes	3,898,000	3,149,000
Change in pension and other postretirement benefit plans, deferred taxes	2,400,000	1,900,000
Change in foreign currency translation adjustment	2,419,000
Change in unrealized loss on hedges, net of deferred taxes	(1,283,000)	(118,000)
Change in unrealized loss on hedges, deferred taxes	800,000	100,000
Change in unrealized gain (loss) on investments, net of deferred taxes	(369,000)	9,626,000
Change in unrealized gain (loss) on investments, deferred taxes	0	5,600,000
Comprehensive income	$ 45,281,000	$ 94,470,000