Common Stock (Basic And Diluted Earnings Per Share) (Details) (USD $) In Thousands, except Share data	3 Months Ended	6 Months Ended	12 Months Ended
Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Common Stock
Basic number of common shares outstanding	41,853,552	43,460,458	42,079,568	43,598,933	42,376,298	43,943,503
Dilutive effect of unvested performance awards	195,078	40,740	182,252	56,542	164,636	56,146
Dilutive effect of stock options	28,029	56,590	36,896	54,551	54,077	59,552
Diluted number of common shares outstanding	42,076,659	43,557,788	42,298,716	43,710,026	42,595,011	44,059,201
Net income	$ 32,990	$ 21,507	$ 39,765	$ 32,956	$ 107,412	$ 74,849
Income allocated to participating restricted stock	(157)	(91)	(179)	(132)	(458)	(287)
Net income available to common shareholders	32,833	21,416	39,586	32,824	106,954	74,562
Income reallocated to participating restricted stock	(157)	(90)	(178)	(132)	(456)	(286)
Net income available to common shareholders	$ 32,833	$ 21,417	$ 39,587	$ 32,824	$ 106,956	$ 74,563
Distributed earnings per share basic	$ 0.22	$ 0.00	$ 0.22	$ 0.00	$ 0.22	$ 0.00
Undistributed earnings per share basic	$ 0.56	$ 0.49	$ 0.72	$ 0.75	$ 2.30	$ 1.70
Basic net income per common share	$ 0.78	$ 0.49	$ 0.94	$ 0.75	$ 2.52	$ 1.70
Distributed earnings per share diluted	$ 0.22	$ 0.00	$ 0.22	$ 0.00	$ 0.22	$ 0.00
Undistributed earnings per share diluted	$ 0.56	$ 0.49	$ 0.72	$ 0.75	$ 2.29	$ 1.69
Diluted net income per common share	$ 0.78	$ 0.49	$ 0.94	$ 0.75	$ 2.51	$ 1.69

The amount of distributed earnings for the period per each share of common stock outstanding during the reporting period.

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The amount of distributed earnings for the period per each share of common stock and dilutive common stock equivalents outstanding during the reporting period.

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Income Allocated To Participating Restricted Stock Basic

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Income Reallocated To Participating Restricted Stock Diluted

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The amount of undistributed earnings for the period per each share of common stock outstanding during the reporting period.

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The amount of undistributed earnings for the period per each share of common stock and dilutive common stock equivalents outstanding during the reporting period.

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

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The amount of net income or loss for the period per each share of common stock and dilutive common stock equivalents outstanding during the reporting period.

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Nonvested share-based payment awards that contain forfeitable rights to dividends or dividend equivalents (whether paid or unpaid) that result in incremental common shares.

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Aggregate awards of share options and nonvested shares to be issued to an employee under a share-based compensation arrangement are considered options for purposes of computing diluted earnings per share. Such share-based awards shall be considered to be outstanding as of the grant date for purposes of computing diluted earnings per share even though their exercise may be contingent upon vesting. Those share-based awards are included in the diluted Earnings Per Share (EPS) computation even if the employee may not receive (or be able to sell) the stock until some future date. Accordingly, all shares to be issued shall be included in computing diluted EPS if the effect is dilutive. The dilutive effect of share-based compensation arrangements shall be computed using the treasury stock method. If the equity share options or other equity instruments are outstanding for only part of a period, the shares issuable shall be weighted to reflect the portion of the period during which the equity instruments were outstanding.

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The portion of consolidated profit or loss for the period, net of income taxes, which is attributable to the parent. If the entity does not present consolidated financial statements, the amount of profit or loss for the period, net of income taxes.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
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-Number 210
-Section 03
-Paragraph 19
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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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Net Income (Loss) Available to Common Stockholders plus adjustments resulting from the assumption that dilutive convertible securities were converted, options or warrants were exercised, or that other shares were issued upon the satisfaction of certain conditions.

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The average number of shares issued and outstanding that are used in calculating diluted EPS, determined based on the timing of issuance of shares in the period.

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

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