Retirement Plans (Details) (USD $)	6 Months Ended			3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010	Jun. 30, 2011 Pension Plans, Defined Benefit [Member]	Jun. 30, 2010 Pension Plans, Defined Benefit [Member]	Jun. 30, 2011 Pension Plans, Defined Benefit [Member]	Jun. 30, 2010 Pension Plans, Defined Benefit [Member]	Jun. 30, 2011 Other Pension Plans, Defined Benefit [Member]	Jun. 30, 2010 Other Pension Plans, Defined Benefit [Member]	Jun. 30, 2011 Other Pension Plans, Defined Benefit [Member]	Jun. 30, 2010 Other Pension Plans, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost				$ 9,615,000	$ 1,609,000	$ 19,230,000	$ 3,218,000	$ 4,228,000	$ 99,000	$ 8,456,000	$ 198,000
Interest cost on projected benefit obligation				21,172,000	12,381,000	42,344,000	24,762,000	6,328,000	2,629,000	12,656,000	5,258,000
Expected return on plan assets				(25,589,000)	(11,649,000)	(51,178,000)	(23,298,000)	(82,000)	(108,000)	(164,000)	(216,000)
Amortization of prior service cost /(credit)				(50,000)	(50,000)	(100,000)	(100,000)	(2,550,000)	(1,929,000)	(5,100,000)	(3,858,000)
Amortization of unrecognized loss				4,435,000	6,748,000	8,870,000	13,496,000	1,499,000	1,581,000	2,998,000	3,162,000
Net periodic benefit cost				9,583,000	9,039,000	19,166,000	18,078,000	9,423,000	2,272,000	18,846,000	4,544,000
Amount capitalized of pension and OPEB expense	6,800,000	3,300,000
Range of full year estimated pension and other postretirement benefit expenses - lower	70,000,000	68,400,000
Range of full year estimated pension and other postretirement benefit expenses - upper	80,000,000	68,400,000
Estimated full year cash contributions to pension plan	50,000,000
Payments made to pension plans	10,600,000
Number of pension plans that were merged with the pension plan	12
Assets transferred into the Plan related to the Transaction	438,800,000
Receivable of the Plan that was transferred related to the Transaction	175,400,000
Amount of pension plan assets	1,301,400,000		1,290,300,000
Amount of increase in pension plan assets	11,100,000
Percentage of increase in pension plan assets (in hundredths)	1.00%
Increase in pension plan assets due to investment returns	56,800,000
Decrease in pension plan assets due to ongoing benefit payments	$ 56,300,000