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, 2013	Mar. 31, 2012
Net Earnings Attributable to Shareholders
Basic earnings attributable to shareholders	$ 80,315	$ 76,707
Diluted earnings attributable to shareholders	$ 80,315	$ 76,707
Weighted Average Shares
Weighted average basic shares outstanding	206,475,095	212,097,662
Effect of dilutive potential common shares	1,138,768	2,101,848
Weighted average diluted shares outstanding	207,613,863	214,199,510
Earnings Per Share
Basic earnings attributable to shareholders per share	$ 0.39	$ 0.36
Diluted earnings attributable to shareholders per share	$ 0.39	$ 0.36

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, 2013

Mar. 31, 2012

Net Earnings Attributable to Shareholders

Basic earnings attributable to shareholders

$ 80,315

$ 76,707

Diluted earnings attributable to shareholders

$ 80,315

$ 76,707

Weighted Average Shares

Weighted average basic shares outstanding

206,475,095

212,097,662

Effect of dilutive potential common shares

1,138,768

2,101,848

Weighted average diluted shares outstanding

207,613,863

214,199,510

Earnings Per Share

Basic earnings attributable to shareholders per share

$ 0.39

$ 0.36

Diluted earnings attributable to shareholders per share

$ 0.39

$ 0.36

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The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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Net income after adjustments for dividends on preferred stock (declared in the period) and/or cumulative preferred stock (accumulated for the period).

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