Postretirement Benefits Other Than Pensions (Details Textual) (USD $)	12 Months Ended
	Dec. 31, 2011 Y	Dec. 31, 2010	Dec. 31, 2001 Y
Postretirement Benefits Other Than Pensions (Textual) [Abstract]
Projected trend of health care cost	7.30%
Eligible retirement age required for these postretirement benefit plan	after attainment of age 55 and completion of 15 years of service, or attainment of age 65 and completion of 10 years of service
Percentage increase in accumulated postretirement benefit obligation due to effect of one percentage point increase in health care cost trend	11.00%
Percentage increase in service and interest cost components of net postretirement benefit expense due to effect of one percentage point increase in health care cost trend	14.00%
Percentage decrease in accumulated postretirement benefit obligation due to effect of one percentage point decrease in health care cost trend	9.00%
Percentage decrease in service and interest cost components of net postretirement benefit expense due to effect of one percentage point decrease in health care cost trend	11.00%
Minimum age of retirement under option one to avail benefit of post retirement	55
Minimum service period served at the time of retirement under option one to avail benefit of post retirement	15 years
Minimum age of retirement under option two to avail benefit of post retirement.	65
Minimum service period served at time of retirement under option two to avail benefit of post retirement	10 years
Minimum for age plus years of service of retirement under amended plan to avail benefit of post retirement			60
Minimum service period served at the time of retirement under amended plan to avail benefit of post retirement			10 years
Prior service credit	$ 1,100,000
Amortization of curtailment gain arising during period before tax	200,000	200,000
Unrecognized actuarial losses	6,000,000	500,000
Unrecognized actuarial losses, net of tax	3,900,000	300,000
Unrecognized Prior service credit	600,000
Unrecognized Prior service credit, Net of Tax	400,000
Unrecognized curtailment gains	100,000	300,000
Unrecognized curtailment gains, net of tax	100,000	200,000
Net loss that will be amortized from accumulated other comprehensive loss into net postretirement benefit expense	700,000
Prior service credit in OCI that will be amortized into net postretirement benefit expense in next fiscal year	400,000
Curtailment gain in OCI that will be amortized into net postretirement benefit expense in next fiscal year	100,000
Amendment in the effective plans			only retirees currently receiving benefits under the plans and active employees whose age plus years of service total at least 60 and who have at least 10 years of service as of December 31, 2001 remain eligible.
Decrease in benefit obligation due to amendment	1,100,000
Other Postretirement Benefit Plans, Defined Benefit [Member]
Postretirement Benefits Other Than Pensions (Additional Textual) [Abstract]
Expected contribution to plan in 2012	1,100,000
Net loss recognized in other comprehensive income	5,500,000	2,300,000
Amortization of prior service credit recognized in other comprehensive income	400,000
Postretirement Benefits Other Than Pensions (Textual) [Abstract]
Prior service credit	$ 1,075,000
Minimum [Member]
Postretirement Benefits Other Than Pensions (Additional Textual) [Abstract]
Trend rate of decline in health care cost	4.00%
Maximum [Member]
Postretirement Benefits Other Than Pensions (Additional Textual) [Abstract]
Trend rate of decline in health care cost	6.00%