CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (UNAUDITED) (Parenthetical) - $ / shares	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Common stock, par value beginning balance	$ 0.001	$ 0.001
Options exercised, shares	80,660	386,616
Conversion of common stock units, shares	8,293	10,834
Conversion of restricted stock units, shares	191,998	168,049
Cash dividends, per share	$ 0.75	$ 0.69
Treasury stock, beginning balance, shares	23,308,430	23,117,554
Treasury stock, acquisition of shares	476,498	190,876
Treasury stock, ending balance, shares	23,784,928	23,308,430,000