Reconciliation of Numerators and Denominators of Basic and Diluted Earnings Per Share (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
Dec. 31, 2013	Dec. 31, 2012
Numerator for diluted and basic earnings per share:
Net income	$ 16,977	$ 23,421
Denominator-share:
Basic weighted-average shares	34,699	35,043
Effect of dilutive securities	1,121	1,108
Diluted weighted-average shares	35,820	36,151
Earnings per share:
Basic	$ 0.49	$ 0.67
Diluted	$ 0.47	$ 0.65

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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The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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- Definition

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

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