Equity (Detail) - Share Repurchase Activity (Parentheticals) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Average purchase price for shares	$ 48.27	$ 34.58	$ 39.51	$ 36.33