Pension Benefits (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Components of Net Periodic Benefit Costs for Both Pension Plans
Defined Benefit Plan, Service Cost	$ 1,232,000	$ 950,000	$ 3,697,000	$ 2,850,000
Defined Benefit Plan, Interest Cost	345,000	296,000	1,034,000	888,000
Defined Benefit Plan, Expected Return on Plan Assets	(286,000)	(220,000)	(858,000)	(660,000)
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	4,000	0	13,000	0
Defined Benefit Plan, Amortization of Gains (Losses)	197,000	102,000	591,000	304,000
Defined Benefit Plan, Net Periodic Benefit Cost	1,492,000	1,128,000	4,477,000	3,382,000
Percentage in excess of the greater of the benefit obligation or the market-related value of assets, gain and losses amortized (as a percent)	10.00%
Required contribution to Qualified Pension Plan for the current fiscal year	$ 5,400,000		$ 5,400,000