CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (Parentheticals) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement Of Stockholders' Equity [Abstract]
Issuance of common stock to non-employee directors, shares	4,620	5,154	4,734
Exercise of stock options, shares	34,000	31,697	102,314
Dividends paid, per share (in dollars per share)	$ 0.64	$ 0.60	$ 0.56