Retirement Pension Plan - Schedule of Weighted Average Assets Allocations (Details)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Defined Benefit Plan Disclosure [Line Items]
Weighted-average assets allocations	100.00%	100.00%	100.00%
Target plan asset allocations for 2013	40.00%
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted-average assets allocations	70.10%	63.50%	62.60%
Target plan asset allocations for 2013	60.00%
Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted-average assets allocations	27.60%	34.90%	35.50%
Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted-average assets allocations	2.30%	1.60%	1.90%
Common Stock [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted-average assets allocations	0.00%	0.00%	0.00%