Consolidated Statements of Changes in Shareholders' Equity (Parenthetical) (Unaudited) (USD $)	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011
Consolidated Statements of Changes In Shareholders' Equity [Abstract]
Common stock, par value	$ 0.001	$ 0.001
Options exercised, shares	190,897	136,290
Conversion of common stock units, shares	10,696	15,715
Conversion of restricted stock units, shares	85,641	170,876
Cash dividends, per share	$ 0.26	$ 0.22
Treasury stock, beginning balance, shares	22,028,030	21,813,196
Treasury stock, acquisition of shares	705,057	60,126
Treasury stock, ending balance, shares	22,733,087	21,873,322