Components Of Equity - Additional Information (Detail) (USD $)	0 Months Ended		9 Months Ended		0 Months Ended
	May 07, 2014	May 01, 2013	Sep. 30, 2014 Non-Discretionary Plan	Sep. 30, 2014 Discretionary Plan	Nov. 04, 2014 Subsequent Event
Class of Stock [Line Items]
Shares repurchased			1,364,974	10,057,648
Average price per share			$ 42.73	$ 41.44
Expected common stock shares issued and outstanding				190,000,000
Date of declaration of dividends	May 07, 2014	May 01, 2013			Nov. 04, 2014
Dividend declared per share	$ 0.32	$ 0.30			$ 0.32
Date of dividend payment	Jun. 16, 2014	Jun. 17, 2013			Dec. 15, 2014
Dividends payable to shareholders date of record	Jun. 02, 2014	Jun. 03, 2013			Dec. 01, 2014