Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Earnings Per Share [Abstract]
Distributed earnings allocated to common stock	$ 6,315us-gaap_DistributedEarnings	$ 6,224us-gaap_DistributedEarnings
Undistributed Earnings, Diluted	11,468us-gaap_UndistributedEarningsDiluted	7,438us-gaap_UndistributedEarningsDiluted
Net Income (Loss) Available to Common Stockholders, Diluted	$ 17,783	$ 13,662
Average shares outstanding (in shares)	15,067,000	15,631,000
Incremental Common Shares Attributable to Dilutive Effect of Call Options and Warrants	62,000	62,000
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements	20,000	103,000
Shares for diluted earnings per share (in shares)	15,149,000	15,796,000
Basic earnings per share (in dollars per share)	$ 1.18us-gaap_EarningsPerShareBasic	$ 0.87us-gaap_EarningsPerShareBasic
Diluted earnings per share (in dollars per share)	$ 1.17us-gaap_EarningsPerShareDiluted	$ 0.86us-gaap_EarningsPerShareDiluted
Options to purchase shares of common stock, anti-dilutive (in shares)	0	0

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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The total amount of dividends declared in the period for each class of stock and the contractual amount of dividends (or interest on participating income bonds) that must be paid for the period (for example, unpaid cumulative dividends). Dividends declared in the current period do not include dividends declared in respect of prior-period unpaid cumulative dividends. Preferred dividends that are cumulative only if earned are deducted only to the extent that they are earned.

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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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Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of call options and warrants using the treasury stock method.

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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 or 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 earnings that is allocated to common stock and participating securities to the extent that each security may share in earnings as if all of the earnings for the period had been distributed. Includes the adjustments resulting from the assumption that dilutive 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 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.

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