Consolidated Statements of Changes in Shareholders' Equity (Unaudited) (Parenthetical) (USD $)	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Consolidated Statements of Changes in Shareholders' Equity [Abstract]
Common stock, par value beginning balance	$ 0.001	$ 0.001
Common stock, par value ending balance	$ 0.001	$ 0.001
Options exercised, shares	563,487	190,897
Conversion of common stock units, shares	11,851	10,696
Conversion of restricted stock units, shares	141,732	85,641
Cash dividends, per share	$ 0.39	$ 0.26
Treasury stock, beginning balance, shares	22,943,925	22,028,030
Treasury stock, acquisition of shares	173,428	705,057
Treasury stock, ending balance, shares	23,117,353	22,733,087