CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (Parenthetical) - $ / shares	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Common stock, par value beginning balance	$ 0.001	$ 0.001
Options exercised, shares	84,850	43,298
Conversion of common stock units, shares	8,538	8,293
Conversion of restricted stock units, shares	165,794	157,539
Cash dividends, per share	$ 0.265	$ 0.250
Treasury stock, beginning balance, shares	23,971,522	23,308,430
Treasury stock, acquisition of shares	474,277	23,500
Treasury stock, ending balance, shares	24,445,799	23,331,930