Pension and Other Post-Retirement Benefit Plans (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Pension Plans [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	$ 0	$ 0	$ 0	$ 0
Interest cost	9,272,000	9,290,000	27,816,000	27,871,000
Expected return on plan assets	(9,970,000)	(9,757,000)	(29,910,000)	(29,271,000)
Amortization of prior service cost	0	0	0	0
Amortization of net loss	2,670,000	675,000	8,010,000	2,025,000
Net periodic benefit cost	1,972,000	208,000	5,916,000	625,000
Employer contributions	18,500,000		22,200,000
Estimated future employer contributions in current fiscal year	2,500,000		2,500,000
Post-Retirement Healthcare Plan [Member]
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	67,000	62,000	201,000	186,000
Interest cost	95,000	97,000	285,000	291,000
Expected return on plan assets	0	0	0	0
Amortization of prior service cost	(1,388,000)	(1,388,000)	(4,164,000)	(4,164,000)
Amortization of net loss	108,000	132,000	324,000	396,000
Net periodic benefit cost	$ (1,118,000)	$ (1,097,000)	$ (3,354,000)	$ (3,291,000)