Net Income Per Share Computations (Narrative) (Details) - $ / shares	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015
Number of common stock shares to purchase under stock options	191,002	223,002
Average price of common shares under stock options	$ 8.51	$ 9.30
Excluded From Diluted Net Income Computation [Member]
Number of common stock shares to purchase under stock options	45,000		75,000
Average price of common shares under stock options	$ 12.80		$ 13.45