Basic and Diluted Earnings per Share - Numerator and Denominator of the Basic and Diluted Per Share Computations for Earnings Attributable to Shareholders Per Share (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Net Earnings Attributable to Shareholders
Basic earnings attributable to shareholders	$ 92,400	$ 88,490	$ 265,030	$ 249,152
Diluted earnings attributable to shareholders	$ 92,400	$ 88,490	$ 265,030	$ 249,152
Weighted Average Shares
Weighted average basic shares outstanding	206,516,194	210,135,763	206,478,746	211,314,850
Effect of dilutive potential common shares	852,598	1,261,839	872,823	1,601,459
Weighted average diluted shares outstanding	207,368,792	211,397,602	207,351,569	212,916,309
Earnings Per Share
Basic earnings attributable to shareholders per share	$ 0.45	$ 0.42	$ 1.28	$ 1.18
Diluted earnings attributable to shareholders per share	$ 0.45	$ 0.42	$ 1.28	$ 1.17

Basic and Diluted Earnings per Share - Numerator and Denominator of the Basic and Diluted Per Share Computations for Earnings Attributable to Shareholders Per Share (Detail) (USD $)
In Thousands, except Share data, unless otherwise specified

3 Months Ended

9 Months Ended

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

Net Earnings Attributable to Shareholders

Basic earnings attributable to shareholders

$ 92,400

$ 88,490

$ 265,030

$ 249,152

Diluted earnings attributable to shareholders

$ 92,400

$ 88,490

$ 265,030

$ 249,152

Weighted Average Shares

Weighted average basic shares outstanding

206,516,194

210,135,763

206,478,746

211,314,850

Effect of dilutive potential common shares

852,598

1,261,839

872,823

1,601,459

Weighted average diluted shares outstanding

207,368,792

211,397,602

207,351,569

212,916,309

Earnings Per Share

Basic earnings attributable to shareholders per share

$ 0.45

$ 0.42

$ 1.28

$ 1.18

Diluted earnings attributable to shareholders per share

$ 0.45

$ 0.42

$ 1.28

$ 1.17

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