Consolidated Statements of Changes in Shareholders' Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Statement Of Stockholders Equity [Abstract]
Exercise of stock options, shares	4,500	11,500
Purchase of treasury shares	23,344	11,218
Sale of treasury shares	11,109	10,489
Dividends declared, per share	$ 0.14	$ 0.10