Employee Pension Plans (Details) (Employee Pension Plans, USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Employee Pension Plans
Summary of net periodic benefit cost
Interest cost	$ 917,000	$ 1,005,000	$ 2,750,000	$ 3,015,000
Expected return on plan assets	(1,121,000)	(1,186,000)	(3,361,000)	(3,558,000)
Amortization of net loss	1,544,000	1,396,000	4,632,000	4,189,000
Net periodic benefit cost	1,340,000	1,215,000	4,021,000	3,646,000
Company contribution			1,100,000	4,700,000
Expected contributions remainder of current fiscal year			$ 600,000