Stock Option Plans (Details 4) (Officer and Employee Plans [Member], USD $)	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013	Dec. 31, 2012
Officer and Employee Plans [Member]
Shares, Outstanding	810,825		670,300	572,600
Shares, Granted	207,000		203,000	202,000
Shares, Exercised	0		0	0
Shares, Forfeited	(77,990)		(62,475)	(104,300)
Shares, Options exercisable	345,735		307,025	274,680
Shares, Outstanding	939,835		810,825	670,300
Weighted Average Exercise Price, Outstanding (in dollars per share)	$ 3.51		$ 3.86	$ 4.63
Weighted Average Exercisable Price Granted (in dollars per share)	$ 2.40		$ 2.37	$ 1.65
Weighted Average Exercisable Price Exercised (in dollars per share)	$ 0		$ 0	$ 0
Weighted Average Exercisable Price Forfeited (in dollars per share)	$ 4.89		$ 3.40	$ 3.89
Weighted Average Exercise Price, Outstanding (in dollars per share)	$ 3.15		$ 3.51	$ 3.86
Weighted Average Exercisable Price, Options exercisable (in dollars per share)	$ 4.88		$ 6.10	$ 6.82
Weighted-average fair value of options granted during the year	$ 1.30		$ 1.17	$ 0.78
Aggregate Intrinsic Value Outstanding	$ 953,940	[1]
Aggregate Intrinsic Value Options exercisable at year end	$ 264,144	[1]

[1] The aggregate intrinsic value of a stock option in the table above represents the total pre-tax intrinsic value (the amount by which the current market value of the underlying stock exceeds the exercise price of the option) that would have been received by the option holders had all option holders exercised their options on December 31, 2014. This amount changes based on changes in the market value of Cornerstone's stock.