CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (Parentheticals) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement Of Stockholders' Equity [Abstract]
Issuance of common stock to non-employee directors, shares	5,154	4,734	4,737
Exercise of stock options, shares	31,697	102,314	153,775
Dividends paid, per share (in dollars per share)	$ 0.60	$ 0.56	$ 0.52