Employee Pension Plans (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Net periodic benefit cost by component [Abstract]
Interest cost	$ 1,005,000	$ 1,108,000	$ 3,015,000	$ 3,323,000
Expected return on plan assets	(1,186,000)	(1,254,000)	(3,558,000)	(3,763,000)
Amortization of net loss	1,396,000	992,000	4,189,000	2,976,000
Net periodic benefit cost	1,215,000	846,000	3,646,000	2,536,000
Contributions to the defined benefit pension plan			4,700,000	5,200,000
Expected contributions to the defined benefit pension plan in remainder of current fiscal year	$ 900,000		$ 900,000