CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (UNAUDITED) (Parenthetical) - $ / shares	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Common stock, par value beginning balance	$ 0.001	$ 0.001
Conversion of common stock units, shares	8,293	10,834
Conversion of restricted stock units, shares	182,888	91,353
Cash dividends, per share	$ 0.50	$ 0.46
Treasury stock, beginning balance, shares	23,308,430	23,117,554
Treasury stock, acquisition of shares	23,500	136,976
Treasury stock, ending balance, shares	23,331,930	23,254,530
Options exercised, shares	74,233	382,956