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	6 Months Ended
Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Net Earnings Attributable to Shareholders
Basic earnings attributable to shareholders	$ 92,315	$ 83,955	$ 172,630	$ 160,662
Diluted earnings attributable to shareholders	$ 92,315	$ 83,955	$ 172,630	$ 160,662
Weighted Average Shares
Weighted average basic shares outstanding	206,444,464	211,724,082	206,459,701	211,910,872
Effect of dilutive potential common shares	748,070	1,488,830	962,104	1,772,715
Weighted average diluted shares outstanding	207,192,534	213,212,912	207,421,805	213,683,587
Earnings Per Share
Basic earnings attributable to shareholders per share	$ 0.45	$ 0.40	$ 0.84	$ 0.76
Diluted earnings attributable to shareholders per share	$ 0.45	$ 0.39	$ 0.83	$ 0.75

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

6 Months Ended

Jun. 30, 2013

Jun. 30, 2012

Jun. 30, 2013

Jun. 30, 2012

Net Earnings Attributable to Shareholders

Basic earnings attributable to shareholders

$ 92,315

$ 83,955

$ 172,630

$ 160,662

Diluted earnings attributable to shareholders

$ 92,315

$ 83,955

$ 172,630

$ 160,662

Weighted Average Shares

Weighted average basic shares outstanding

206,444,464

211,724,082

206,459,701

211,910,872

Effect of dilutive potential common shares

748,070

1,488,830

962,104

1,772,715

Weighted average diluted shares outstanding

207,192,534

213,212,912

207,421,805

213,683,587

Earnings Per Share

Basic earnings attributable to shareholders per share

$ 0.45

$ 0.40

$ 0.84

$ 0.76

Diluted earnings attributable to shareholders per share

$ 0.45

$ 0.39

$ 0.83

$ 0.75

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