Common Shares, Treasury Shares, Reserves and Dividends - Additional Information (Detail) - USD ($)			1 Months Ended	3 Months Ended												12 Months Ended
	Mar. 09, 2017	Oct. 05, 2016	Dec. 31, 2016	Jan. 28, 2017	Oct. 29, 2016	Jul. 30, 2016	Apr. 30, 2016	Jan. 30, 2016	Oct. 31, 2015	Aug. 01, 2015	May 02, 2015	Jan. 31, 2015	Nov. 01, 2014	Aug. 02, 2014	May 03, 2014	Jan. 28, 2017	Jan. 30, 2016	Jan. 31, 2015	Aug. 31, 2016	Feb. 29, 2016
Class of Stock [Line Items]
Common shares, par value (usd per share)				$ 0.18				$ 0.18								$ 0.18	$ 0.18
Proceeds from issuance of common shares																$ 2,100,000	$ 5,000,000	$ 6,100,000
Shares repurchased (shares)																11,200,000	1,000,000	300,000
Amount repurchased																$ 1,000,000,000	$ 130,000,000	$ 29,800,000
Average repurchase price per share (usd per share)																$ 89.10	$ 127.63	$ 103.37
Treasury stock held (shares)				18,900,000				7,800,000								18,900,000	7,800,000
Treasury stock reissued																100,000	200,000
Dividends declared per common share (usd per share)				$ 0.26	$ 0.26	$ 0.26	$ 0.26	$ 0.22	$ 0.22	$ 0.22	$ 0.22	$ 0.18	$ 0.18	$ 0.18	$ 0.18	$ 1.04	$ 0.88	$ 0.72
Dividends on preferred shares				$ 17,700,000				$ 17,500,000								$ 17,700,000	$ 17,500,000
Cumulative undeclared dividends																0
Dividends on redeemable convertible preferred shares																11,900,000
Subsequent Event
Class of Stock [Line Items]
Dividends declared date	Mar. 09, 2017
Dividends declared per common share (usd per share)	$ 0.31
Dividends payable date	May 31, 2017
Dividends payable, date of record	Apr. 28, 2017
2016 Program
Class of Stock [Line Items]
Amount authorized				1,375,000,000												$ 1,375,000,000			$ 625,000,000	$ 750,000,000
Shares repurchased (shares)																10,004,333
Amount repurchased																$ 864,400,000
Average repurchase price per share (usd per share)																$ 86.40
Accelerated Share Repurchase Program
Class of Stock [Line Items]
Accelerated share repurchases, payment		$ 525,000,000
Shares repurchased (shares)		4,700,000	1,300,000													6,000,000
Amount repurchased		$ 367,500,000
Average repurchase price per share (usd per share)																$ 87.01
Common Stock
Class of Stock [Line Items]
Shares repurchased (shares)																5,200,000
Amount repurchased																$ 475,000,000
Series A Redeemable Convertible Preferred Stock
Class of Stock [Line Items]
Dividends on preferred shares				$ 11,300,000												11,300,000
Dividends on redeemable convertible preferred shares																$ 600,000