Per Share Information - Basic and Diluted Earnings Per Share (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
AMOUNTS ATTRIBUTABLE TO COMMON STOCK:
Net income from continuing operations	$ 92,906	$ 83,628	$ 235,224	$ 187,344
Net income from discontinued operations		12,770		20,299
Net income attributable to common stock	$ 92,906	$ 96,398	$ 235,224	$ 207,643
WEIGHTED AVERAGE SHARES:
Weighted average shares outstanding for basic earnings per share	214,866	213,150	214,178	212,564
Effect of dilutive stock options	50	92	51	86
Weighted average shares outstanding for diluted earnings per share	214,916	213,242	214,229	212,650

Amount of income (loss) from continuing operations attributable to the parent. Also defined as revenue less expenses and taxes from ongoing operations before extraordinary items but after deduction of those portions of income or loss from continuing operations that are allocable to noncontrolling interests.

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Amount of income (loss) from a disposal group, net of income tax, reported as a separate component of income before extraordinary items after deduction or consideration of the amount allocable to noncontrolling interests. Includes, net of tax, income (loss) from operations during the phase-out period, gain (loss) on disposal, provision (or any reversals of earlier provisions) for loss on disposal, and adjustments of a prior period gain (loss) on disposal.

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Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of share based payment arrangements using the treasury stock method.

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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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