Note 2 - Significant Accounting Policies and Consolidated Financial Statement Components (Details Textual) $ in Thousands			1 Months Ended		3 Months Ended			12 Months Ended
	Jan. 01, 2019 USD ($)	Jun. 01, 2018 USD ($)	Mar. 31, 2019 USD ($)	Jul. 30, 2018 USD ($)	Mar. 31, 2019 USD ($)	Sep. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Mar. 31, 2019 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2015 USD ($)
Loans and Leases Receivable, Deferred Income, Total			$ 47,251		$ 47,251			$ 47,251		$ 43,897
Weighted Average Remaining Accretion Period of Deferred Revenue					330 days
Unamortized Loan Commitment and Origination Fees and Unamortized Discounts or Premiums, Total			29,500		$ 29,500			$ 29,500		30,000
Financing Receivable, Modifications, Number of Contracts								19,383	15,723
Financing Receivable, Troubled Debt Restructuring			29,200		$ 29,200		$ 26,400	$ 29,200	$ 26,400
Effective Income Tax Rate Reconciliation, Percent, Total					4.00%		3.10%
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense, Total					$ 100		$ 200
Income Tax Settlement Amount with Taxing Authority											$ 7,400
Tax Adjustments, Settlements, and Unusual Provisions		$ 3,700
Payment of Income Tax Settlement			200	$ 5,400
Proceeds from Income Tax Refunds						$ 500
Abatement Sought for Failure-to-pay Penalties			900		900			900
Reclassification from Unrestricted Cash and Cash Equivalents					26,000
Operating Lease, Liability, Total			27,742		27,742			27,742
Operating Lease, Right-of-Use Asset			17,013		17,013			17,013
Accounting Standards Update 2016-02 [Member]
Operating Lease, Liability, Total	$ 30,200
Operating Lease, Right-of-Use Asset	18,600
Cumulative Effect on Retained Earnings, before Tax	$ 600
Accounts Payable and Accrued Liabilities [Member]
Accrual of Customer Claims			$ 92,000		92,000			$ 92,000
Other Income [Member]
Reduction in Accruals					$ 15,500