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
Mar. 31, 2012	Mar. 31, 2011
Net Earnings Attributable to Shareholders
Basic earnings attributable to shareholders	$ 76,707	$ 91,232
Diluted earnings attributable to shareholders	$ 76,707	$ 91,232
Weighted Average Shares
Weighted average basic shares outstanding	212,097,662	212,088,860
Effect of dilutive potential common shares	2,101,848	3,774,526
Weighted average diluted shares outstanding	214,199,510	215,863,386
Earnings Per Share
Basic earnings attributable to shareholders	$ 0.36	$ 0.43
Diluted earnings attributable to shareholders	$ 0.36	$ 0.42

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

Mar. 31, 2012

Mar. 31, 2011

Net Earnings Attributable to Shareholders

Basic earnings attributable to shareholders

$ 76,707

$ 91,232

Diluted earnings attributable to shareholders

$ 76,707

$ 91,232

Weighted Average Shares

Weighted average basic shares outstanding

212,097,662

212,088,860

Effect of dilutive potential common shares

2,101,848

3,774,526

Weighted average diluted shares outstanding

214,199,510

215,863,386

Earnings Per Share

Basic earnings attributable to shareholders

$ 0.36

$ 0.43

Diluted earnings attributable to shareholders

$ 0.36

$ 0.42

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