Stock Option Plans (Details 1) (Board Of Directors Plan [Member], USD $)	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013	Dec. 31, 2012
Board Of Directors Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares, Outstanding	190,250		145,250	55,250
Shares, Granted	80,000		45,000	90,000
Shares, Exercised	0		0	0
Shares, Forfeited	16,000		0	0
Shares, Outstanding	254,250		190,250	145,250
Shares, Options exercisable	151,750		100,250	55,250
Weighted Average Exercise Price, Outstanding (in dollars per share)	$ 3.07		$ 3.30	$ 5.98
Weighted Average Exercise Price, Granted (in dollars per share)	$ 2.40		$ 2.37	$ 1.65
Weighted Average Exercise Price, Exercised (in dollars per share)	$ 0		$ 0	$ 0
Weighted Average Exercise Price, Forfeited (in dollars per share)	$ 5.44		$ 0	$ 0
Weighted Average Exercise Price, Outstanding (in dollars per share)	$ 2.71		$ 3.07	$ 3.30
Weighted Average Exercise Price, Options exercisable (in dollars per share)	$ 2.93		$ 4.03	$ 5.98
Weighted-average fair value of options granted during the year	$ 1.30		$ 1.17	$ 0.78
Aggregate Intrinsic Value, Outstanding	$ 264,500
Aggregate Intrinsic Value, Options exercisable at year end	$ 170,550	[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.