Pension Plan and Postretirement Benefits Other Than Pension (Details 2) (USD $)	3 Months Ended			1 Months Ended	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2014 Pension Benefits	Mar. 31, 2013 Pension Benefits	Apr. 30, 2014 Pension Benefits Subsequent Event	Mar. 31, 2014 Other Postretirement Benefits	Mar. 31, 2013 Other Postretirement Benefits
Components of net periodic benefit cost:
Service cost		$ 2,725,000	$ 2,950,000		$ 180,000	$ 197,000
Interest cost		2,153,000	1,952,000		99,000	90,000
Expected return on plan assets		(3,413,000)	(2,704,000)
Actuarial (gain) loss amortization		411,000	1,250,000		(4,000)
Prior service cost amortization		130,000	139,000		14,000	14,000
Transition obligation amortization		1,000	1,000
Total		2,007,000	3,588,000		289,000	301,000
Percentage of net periodic pension and other postretirement benefit costs included in Compensation and related costs	60.00%
Expected benefit payments
Employer contributions		$ 10,000,000		$ 10,000,000