Consolidated Statements of Comprehensive Earnings (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Amounts Reclassified Out Of Accumulated Other Comprehensive Income Loss [Abstract]
NET EARNINGS	$ 23,997us-gaap_NetIncomeLoss	$ 22,336us-gaap_NetIncomeLoss
OTHER ITEMS OF COMPREHENSIVE EARNINGS:
Change in unrealized gain on investment securities available-for-sale, before income taxes	13,483	21,560
Reclassification adjustment for realized losses (gains) on investment securities included in net earnings, before income taxes	(5)	4
Total other items of comprehensive earnings (losses)	13,478	21,564
Income tax (expense) related to other items of comprehensive earnings	(4,717)us-gaap_OtherComprehensiveIncomeLossTax	(7,547)us-gaap_OtherComprehensiveIncomeLossTax
COMPREHENSIVE EARNINGS	$ 32,758us-gaap_ComprehensiveIncomeNetOfTax	$ 36,353us-gaap_ComprehensiveIncomeNetOfTax

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Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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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 before tax, after reclassification adjustments of other comprehensive income (loss).

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Amount before tax of reclassification adjustment from accumulated other comprehensive income for unrealized gain (loss) realized upon the sale of available-for-sale securities.

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Amount of tax expense (benefit) allocated to other comprehensive income (loss).

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Amount before tax and reclassification adjustments of unrealized holding gain (loss) on available-for-sale securities.

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