CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Statement of Comprehensive Income [Abstract]
NET INCOME	$ 54,165us-gaap_NetIncomeLoss	$ 46,555us-gaap_NetIncomeLoss	$ 64,882us-gaap_NetIncomeLoss
OTHER COMPREHENSIVE INCOME (LOSS), NET OF INCOME TAXES:
Unrealized holding gain (loss) on securities—available-for-sale arising during the period	4,237	(7,835)	28
Income tax benefit (expense) related to securities—available-for-sale unrealized holding gains (losses)	(1,525)	2,813	(10)
Reclassification for net (gains) losses on securities—available-for-sale realized in earnings	41	(116)	38
Income tax benefit (expense) related to securities—available-for-sale realized (gains) losses	(15)	42	(14)
Amortization of unrealized gain on tax exempt securities transferred from available-for-sale to held-to-maturity	0	0	8
Other comprehensive income (loss)	2,738	(5,096)	50
COMPREHENSIVE INCOME	$ 56,903us-gaap_ComprehensiveIncomeNetOfTax	$ 41,459us-gaap_ComprehensiveIncomeNetOfTax	$ 64,932us-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 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 before tax and reclassification adjustments of unrealized holding gain (loss) on available-for-sale securities.

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