Consolidated Statements of Changes in Shareholders' Equity (USD $) In Thousands, unless otherwise specified	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]
Balance at Dec. 31, 2013	$ 571,306us-gaap_StockholdersEquity	$ 77,993	$ 78,140	$ 468,158	$ (12,694)	$ (40,291)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	14,033us-gaap_NetIncomeLoss			14,033
Other comprehensive income (loss), net of tax	3,046				3,046
Cash dividends declared	(4,758)us-gaap_DividendsCommonStockCash			(4,758)
Treasury stock issued for restricted awards	(161)			357		(518)
Recognition of restricted stock compensation expense	185		185
Balance at Mar. 31, 2014	583,651us-gaap_StockholdersEquity	77,993	78,325	477,790	(9,648)	(40,809)
Balance at Dec. 31, 2014	608,389us-gaap_StockholdersEquity	77,993	78,818	504,060	(13,833)	(38,649)
Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs			(123)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	12,835us-gaap_NetIncomeLoss			12,835
Other comprehensive income (loss), net of tax	3,805				3,805
Cash dividends declared	(5,357)us-gaap_DividendsCommonStockCash			(5,357)
Common stock issued in acquisition	142,469	12,333	130,136
Treasury stock issued for restricted awards	(79)			(1,963)		1,884
Recognition of restricted stock compensation expense	319		319
Issuance costs	(123)
Balance at Mar. 31, 2015	$ 762,258us-gaap_StockholdersEquity	$ 90,326	$ 209,150	$ 509,575	$ (10,028)	$ (36,765)

Amount of other increase (decrease) in additional paid in capital (APIC).

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This element represents the amount of recognized equity-based compensation related to other long-term incentive plans during the period, that is, the amount recognized as expense in the income statement (or as asset if compensation is capitalized).

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Amount of decrease in additional paid in capital (APIC) resulting from direct costs associated with issuing stock. Includes, but is not limited to, legal and accounting fees and direct costs associated with stock issues under a shelf registration.

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Amount of paid and unpaid common stock dividends declared with the form of settlement in cash.

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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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Value of stock issued pursuant to acquisitions during the period.

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Value of stock related to Restricted Stock Awards issued during the period, net of the stock value of such awards forfeited.

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