Consolidated Condensed Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Statement of Comprehensive Income [Abstract]
Net Income	$ 19,044us-gaap_NetIncomeLoss	$ 19,577us-gaap_NetIncomeLoss
Other comprehensive income, net of tax:
Unrealized net holding gain on securities available-for-sale, net of income taxes	7,859	10,941
Other comprehensive income (loss)	7,859	10,941
Comprehensive income	$ 26,903us-gaap_ComprehensiveIncomeNetOfTax	$ 30,518us-gaap_ComprehensiveIncomeNetOfTax

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

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

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