Pension Benefits (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Components of Net Periodic Benefit Costs for Both Pension Plans
Service cost	$ 1,584,000	$ 1,572,000	$ 4,752,000	$ 4,718,000
Interest cost	548,000	407,000	1,643,000	1,220,000
Expected return on plan assets that reduces periodic pension costs	(494,000)	(384,000)	(1,483,000)	(1,153,000)
Amortization of prior service costs	4,000	4,000	13,000	13,000
Amortization of net actuarial loss	172,000	306,000	516,000	917,000
Net periodic benefit cost	1,814,000	1,905,000	5,441,000	5,715,000
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%		10.00%
Defined Benefit Plan, Contributions by Employer			$ 5,300,000