Common Stock Plans (Stock Repurchase Program) (Details) (Common Stock, USD $)	0 Months Ended	12 Months Ended
	May 25, 1994	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Common Stock
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program, authorized amount	$ 12,564,400
Stock repurchase program, remaining authorized repurchase amount		$ 8,992,700
Shares acquired in connection with stock compensation plans		5,459	12,867	62,794