Pension Plan and Postretirement Benefits Other Than Pension (Details 2) (USD $)	1 Months Ended	3 Months Ended
	Apr. 30, 2013	Mar. 31, 2013	Mar. 31, 2012
Pension Benefits
Components of net periodic benefit cost:
Service cost		$ 2,950,000	$ 2,209,000
Interest cost		1,952,000	1,812,000
Expected return on plan assets		(2,704,000)	(2,127,000)
Actuarial loss amortization		1,250,000	1,021,000
Prior service cost amortization		139,000	139,000
Transition obligation amortization		1,000	1,000
Total		3,588,000	3,055,000
Net periodic pension benefit cost related to discontinued operations			196,000
Expected benefit payments
Entity's contribution to Pension Plan	7,000,000	10,000,000
Other Postretirement Benefits
Components of net periodic benefit cost:
Service cost		197,000	173,000
Interest cost		90,000	100,000
Actuarial loss amortization			3,000
Prior service cost amortization		14,000	14,000
Total		301,000	290,000
Net periodic pension benefit cost related to discontinued operations			$ 3,000