Earnings Per Share (Details) (USD $) In Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Earnings Per Share, Basic and Diluted
Net earnings	$ 60,437	$ 93,063	$ 176,905	$ 247,797
Less: net earnings attributable to unvested restricted stock and restricted stock units	(950)	(1,067)	(2,551)	(2,746)
Net earnings available to common stock	$ 59,487	$ 91,996	$ 174,354	$ 245,051
Weighted-average common shares outstanding	106,919	114,002	110,665	113,872
Dilutive effect of outstanding options (determined using treasury stock method)	129	156	245	254
Weighted-average common shares and potential common shares outstanding	107,048	114,158	110,910	114,126
Anti-dilutive stock options not included in treasury stock method computation	2,744	4,978	2,279	4,431

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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-URI http://asc.fasb.org/extlink&oid=6510752

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-URI http://asc.fasb.org/extlink&oid=6508534

+ Details

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

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-Name Regulation S-X (SX)

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+ Details

- Definition

The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

+ References+ Details

- Definition

Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period.

+ References

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