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Common Stock and Dividends (Details) (USD $)	0 Months Ended					1 Months Ended	9 Months Ended
	Oct. 15, 2014	Apr. 18, 2014	Apr. 09, 2014	Oct. 15, 2013	Apr. 20, 2013	Apr. 30, 2014	Sep. 30, 2014	Nov. 05, 2014	Mar. 31, 2014	Mar. 07, 2014
Common Stock and Dividends
Series A cumulative perpetual preferred shares, outstanding							216,000
Warrants to purchase entity's common stock (in shares)							1,326,238
Warrants, exercise price (in dollars per share)							$ 24.43
Percentage of aggregate common stock investment on exercise of warrant to Senior Preferred Stock investment							15.00%
Warrants, term							10 years
Cash dividends paid to common shareholders (in dollars per share)	$ 0.27	$ 0.25		$ 0.23	$ 0.20
Repurchase of common stock, authorized amount									$ 40,000,000	$ 40,000,000
Period of repurchase of common stock			12 months			12 months
Cumulative number of shares repurchased under all stock repurchase programs								8,489,280
Cumulative cost of shares repurchased under all stock repurchase programs								$ 252,989,000

X

- Definition

The percentage of aggregate common stock investment on the exercise of warrant to the Senior Preferred Stock investment.

+ References

No definition available.

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X

- Definition

Period representing the term of warrant.

+ References

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X

- Definition

The cumulative cost of shares that have been repurchased under all stock repurchase programs as of a certain date.

+ References

No definition available.

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- Definition

The cumulative number of shares that have been repurchased under all stock repurchase programs as of a certain date.

+ References

No definition available.

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- Definition

Exercise price per share or per unit of warrants or rights outstanding.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.4-08.(i)(4))

-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

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- Definition

Number of securities into which the class of warrant or right may be converted. For example, but not limited to, 500,000 warrants may be converted into 1,000,000 shares.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.4-08.(i)(2))

-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 08

-Paragraph i

-Subparagraph 2

-Article 4

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- Definition

Aggregate dividends paid during the period for each share of common stock outstanding.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.3-04)

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- Definition

Aggregate share number for all nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer) held by stockholders. Does not include preferred shares that have been repurchased.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.28)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 29

-Article 5

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- Definition

Amount of stock repurchase plan authorized.

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- Definition

Period which shares may be purchased under a stock repurchase plan authorized by an entity's Board of Directors, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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