Components Of Equity - Additional Information (Detail) - $ / shares				9 Months Ended
	Nov. 03, 2015	May. 06, 2015	May. 07, 2014	Sep. 30, 2015	Sep. 30, 2014
Class of Stock [Line Items]
Date of declaration of dividends		May 06, 2015	May 07, 2014
Dividend declared per share		$ 0.36	$ 0.32
Date of dividend payment		Jun. 15, 2015	Jun. 16, 2014
Dividends payable to shareholders date of record		Jun. 01, 2015	Jun. 02, 2014
Non-Discretionary Plan
Class of Stock [Line Items]
Shares repurchased				2,242,579	1,364,974
Average price per share				$ 47.93	$ 42.73
Discretionary Plan
Class of Stock [Line Items]
Shares repurchased				6,395,506	10,057,648
Average price per share				$ 48.16	$ 41.44
Expected common stock shares issued and outstanding				180,000,000
Subsequent Event
Class of Stock [Line Items]
Date of declaration of dividends	Nov. 03, 2015
Dividend declared per share	$ 0.36
Date of dividend payment	Dec. 15, 2015
Dividends payable to shareholders date of record	Dec. 01, 2015