Note 12 - Income Taxes (Details) - Reconciliation of Income Tax Expense (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Reconciliation of Income Tax Expense [Abstract]
Tax provision at federal statutory rate	$ 29,818,000	$ 35,762,000	$ 32,718,000
Increase (decrease) in income taxes resulting from:
State, net of federal benefit	2,207,000	2,325,000	3,261,000
Nondeductible expenses	363,000	197,000	118,000
Insurance expense	27,000	35,000	39,000
Other, net	439,000	(258,000)	823,000
Unrecognized tax benefits	512,000	1,107,000	409,000
Expiration of statute of limitations	(1,542,000)	(1,605,000)	(3,187,000)
	2,006,000us-gaap_IncreaseDecreaseInIncomeTaxes	1,801,000us-gaap_IncreaseDecreaseInIncomeTaxes	1,463,000us-gaap_IncreaseDecreaseInIncomeTaxes
Effective income tax expense	$ 31,824,000us-gaap_IncomeTaxExpenseBenefit	$ 37,563,000us-gaap_IncomeTaxExpenseBenefit	$ 34,181,000us-gaap_IncomeTaxExpenseBenefit

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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

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The amount of income tax expense or benefit for the period computed by applying the domestic federal statutory tax rates to pretax income from continuing operations.

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to tax exempt income, equity in earnings (loss) of an unconsolidated subsidiary, minority noncontrolling interest income (loss), tax holiday, disposition of a business, disposition of an asset, repatriation of foreign earnings, repatriation of foreign earnings jobs creation act of 2004, increase (decrease) in enacted tax rate, prior year income taxes, increase (decrease) in deferred tax asset valuation allowance, and other adjustments.

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The increase (decrease) during the reporting period in the amounts payable to taxing authorities for taxes that are based on the reporting entity's earnings, net of amounts receivable from taxing authorities for refunds of overpayments or recoveries of income taxes, and in deferred and other tax liabilities and assets.

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Amount of decrease in unrecognized tax benefits resulting from lapses of applicable statutes of limitations.

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