Pension Benefits (Details) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Components of Net Periodic Benefit Costs for Both Pension Plans
Defined Benefit Plan, Service Cost	$ 1,232,000	$ 950,000
Defined Benefit Plan, Interest Cost	345,000	296,000
Defined Benefit Plan, Expected Return on Plan Assets	(286,000)	(220,000)
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	4,000	0
Defined Benefit Plan, Amortization of Gains (Losses)	197,000	101,000
Defined Benefit Plan, Net Periodic Benefit Cost	1,492,000	1,127,000
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	$ 373,000