Pension and Postretirement Benefits (Net Periodic Benefit Cost-Income) (Details) (USD $)	9 Months Ended	12 Months Ended	3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended
	Sep. 30, 2011	Dec. 31, 2010	Sep. 30, 2011 Pension [Member]	Sep. 30, 2010 Pension [Member]	Sep. 30, 2011 Pension [Member]	Sep. 30, 2010 Pension [Member]	Sep. 30, 2011 Postretirement [ Member]	Sep. 30, 2010 Postretirement [ Member]	Sep. 30, 2011 Postretirement [ Member]	Sep. 30, 2010 Postretirement [ Member]
Service cost			$ 800,000	$ 1,000,000	$ 3,700,000	$ 3,200,000		$ 100,000	$ 100,000	$ 100,000
Interest cost			4,100,000	4,500,000	12,700,000	13,500,000	200,000	300,000	700,000	1,000,000
Expected return on assets			(6,200,000)	(5,600,000)	(18,400,000)	(16,800,000)	(100,000)		(200,000)	(200,000)
Actuarial (gain) / loss			1,700,000	2,000,000	6,200,000	5,600,000	(500,000)	(200,000)	(900,000)	(600,000)
Prior service cost			500,000	900,000	1,600,000	2,800,000	100,000		100,000	100,000
Net periodic benefit cost / (income) before adjustments			900,000	2,800,000	5,800,000	8,300,000	(300,000)	200,000	(200,000)	400,000
Difference between market related value of assets in years	5
Difference between actual and estimated asset returns in MRVA	3
Market related value of assets		$ 317,000,000