Employee Benefit Plans (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Employee Benefit Plans (Textual) [Abstract]
Company contribution to the pension plan			$ 43,000,000
Pension Benefits [Member]
Components of Net Periodic Benefit Cost
Service cost	3,440,000	1,711,000	9,822,000	9,216,000
Interest cost	24,807,000	23,055,000	72,948,000	71,598,000
Expected return on plan assets	(30,918,000)	(28,564,000)	(93,044,000)	(85,582,000)
Amortization of prior service credit	(1,720,000)	(1,745,000)	(5,223,000)	(5,228,000)
Amortization of actuarial loss	14,417,000	7,623,000	39,766,000	26,444,000
Net periodic benefit cost	10,026,000	2,080,000	24,269,000	16,448,000
Other Postretirement Benefits [Member]
Components of Net Periodic Benefit Cost
Interest cost	123,000	143,000	356,000	455,000
Amortization of prior service credit	(168,000)	(264,000)	(698,000)	(794,000)
Amortization of actuarial loss	415,000	423,000	1,282,000	1,319,000
Net periodic benefit cost	$ 370,000	$ 302,000	$ 940,000	$ 980,000