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, 2015	Mar. 31, 2014
Net Earnings Attributable to Shareholders
Basic earnings attributable to shareholders	$ 106,704	$ 83,824
Diluted earnings attributable to shareholders	$ 106,704	$ 83,824
Weighted Average Shares
Weighted average basic shares outstanding	191,627,750	201,118,390
Effect of dilutive potential common shares	1,079,343	725,468
Weighted average diluted shares outstanding	192,707,093	201,843,858
Earnings Per Share
Basic earnings attributable to shareholders per share	$ 0.56us-gaap_EarningsPerShareBasic	$ 0.42us-gaap_EarningsPerShareBasic
Diluted earnings attributable to shareholders per share	$ 0.55us-gaap_EarningsPerShareDiluted	$ 0.42us-gaap_EarningsPerShareDiluted

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, 2015

Mar. 31, 2014

Net Earnings Attributable to Shareholders

Basic earnings attributable to shareholders

$ 106,704us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic

$ 83,824us-gaap_NetIncomeLossAvailableToCommonStockholdersBasic

Diluted earnings attributable to shareholders

$ 106,704us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted

$ 83,824us-gaap_NetIncomeLossAvailableToCommonStockholdersDiluted

Weighted Average Shares

Weighted average basic shares outstanding

191,627,750us-gaap_WeightedAverageNumberOfSharesOutstandingBasic

201,118,390us-gaap_WeightedAverageNumberOfSharesOutstandingBasic

Effect of dilutive potential common shares

1,079,343us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment

725,468us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment

Weighted average diluted shares outstanding

192,707,093us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding

201,843,858us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding

Earnings Per Share

Basic earnings attributable to shareholders per share

$ 0.56us-gaap_EarningsPerShareBasic

$ 0.42us-gaap_EarningsPerShareBasic

Diluted earnings attributable to shareholders per share

$ 0.55us-gaap_EarningsPerShareDiluted

$ 0.42us-gaap_EarningsPerShareDiluted

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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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