Pension Benefits (Details) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Components of Net Periodic Benefit Costs for Both Pension Plans
Service cost	$ 1,573,000	$ 1,232,000
Interest cost	407,000	345,000
Expected return on plan assets that reduces periodic pension costs	(385,000)	(286,000)
Amortization of prior service costs	4,000	4,000
Amortization of net actuarial loss	306,000	197,000
Net periodic benefit cost	1,905,000	1,492,000
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%
Defined Benefit Plan, Contributions by Employer	$ 5,300,000