Consolidated Statements Of Shareholders' Equity (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock and Paid-in Capital [Member]	Accumulated Other Comprehensive Loss [Member]	Retained Earnings [Member]
Balance at Dec. 31, 2013	$ 572,448us-gaap_StockholdersEquity	$ 0	$ (60,086)	$ 632,534
Balance (in shares) at Dec. 31, 2013		13,099,356
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	57,523us-gaap_NetIncomeLoss			57,523
Other comprehensive income (loss)	1,731		1,731
Cash dividends	(14,200)us-gaap_DividendsCommonStockCash			(14,200)
Repurchases of common stock (in shares)		(232,200)
Repurchases of common stock	(81,491)	(472)		(81,019)
Stock-based compensation (in shares)		(121)
Stock-based compensation	474	472		2
Balance at Mar. 31, 2014	536,485us-gaap_StockholdersEquity	0	(58,355)	594,840
Balance (in shares) at Mar. 31, 2014		12,867,035
Balance at Dec. 31, 2014	421,041us-gaap_StockholdersEquity	0	(139,160)	560,201
Balance (in shares) at Dec. 31, 2014	12,446,365us-gaap_CommonStockSharesOutstanding	12,446,365
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	63,947us-gaap_NetIncomeLoss			63,947
Other comprehensive income (loss)	(24,307)		(24,307)
Cash dividends	(17,421)us-gaap_DividendsCommonStockCash			(17,421)
Repurchases of common stock (in shares)		(2,629)
Repurchases of common stock	(1,042)	(232)		(810)
Stock-based compensation (in shares)		(495)
Stock-based compensation	672	658		14
Balance at Mar. 31, 2015	$ 442,890us-gaap_StockholdersEquity	$ 426	$ (163,467)	$ 605,931
Balance (in shares) at Mar. 31, 2015	12,443,241us-gaap_CommonStockSharesOutstanding	12,443,241

This element represents the amount of recognized equity-based compensation during the period, that is, the amount recognized as expense in the income statement (or as asset if compensation is capitalized). Alternate captions include the words "stock-based compensation".

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Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.

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

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Amount after tax of other comprehensive income (loss) attributable to parent entity.

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Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity.

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Number of shares (or other type of equity) issued during the period as a result of any equity-based compensation plan other than an employee stock ownership plan (ESOP), net of any shares forfeited. Shares issued could result from the issuance of restricted stock, the exercise of stock options, stock issued under employee stock purchase plans, and/or other employee benefit plans.

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Number of shares that have been repurchased during the period and have not been retired and are not held in treasury. Some state laws may govern the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

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Equity impact of the value of stock that has been repurchased during the period and has not been retired and is not held in treasury. Some state laws may mandate the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

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