Consolidated Statements Of Stockholders' Equity And Comprehensive Income (Parenthetical) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Consolidated Statements Of Stockholders' Equity And Comprehensive Income [Abstract]
Dividends declared per share	$ 0.7	$ 1.8	$ 1.45
Exercise of stock options, shares	202,578	748,486	320,245