Pension Benefit Cost (Details Textual) (USD $)	9 Months Ended
	Sep. 30, 2012
Pension Benefit Cost (Textual) [Abstract]
Percentage of matching contribution level 1	50.00%
Percentage of Employer contribution level 1	2.00%
Percentage of matching contribution level 2	25.00%
Percentage of Employer contribution level 2	6.00%
Defined benefit pension plans [Member]
Pension Benefit Cost (Textual) [Abstract]
Employer contributions	2,700,000
Supplemental pension plans [Member]
Pension Benefit Cost (Textual) [Abstract]
Employer contributions	400,000
Estimated contribution to defined benefit pension plan	100,000
Postretirement benefit plans [Member]
Pension Benefit Cost (Textual) [Abstract]
Employer contributions	100,000
Estimated contribution to defined benefit pension plan	100,000