Note 17 - Fair Value Measurements - Schedule of Hierarchy and Fair Value for Each Major Category of Assets and Liabilities Measured at Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Assets measured at fair value		$ 126,069
Fair Value, Inputs, Level 1 [Member]
Assets measured at fair value		0
Fair Value, Inputs, Level 2 [Member]
Assets measured at fair value		126,069
Fair Value, Inputs, Level 3 [Member]
Assets measured at fair value		0
Fair Value, Recurring [Member]
Assets measured at fair value	$ 214,662
Fair Value, Recurring [Member] \| US Government Agencies Debt Securities [Member]
Assets measured at fair value	1,288	1,572
Fair Value, Recurring [Member] \| Small Business Administration Agency Securities [Member]
Assets measured at fair value	4,515	4,691
Fair Value, Recurring [Member] \| Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Assets measured at fair value	17,818	19,171
Fair Value, Recurring [Member] \| Collateralized Mortgage Obligations [Member]
Assets measured at fair value	46,336	11,654
Fair Value, Recurring [Member] \| Commercial Paper [Member]
Assets measured at fair value	109,188	69,898
Fair Value, Recurring [Member] \| Corporate Debt Securities [Member]
Assets measured at fair value	33,930	19,083
Fair Value, Recurring [Member] \| Municipal Securities [Member]
Assets measured at fair value	1,587
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Assets measured at fair value	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| US Government Agencies Debt Securities [Member]
Assets measured at fair value	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Small Business Administration Agency Securities [Member]
Assets measured at fair value	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Assets measured at fair value	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Collateralized Mortgage Obligations [Member]
Assets measured at fair value	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Commercial Paper [Member]
Assets measured at fair value	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Corporate Debt Securities [Member]
Assets measured at fair value	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Municipal Securities [Member]
Assets measured at fair value	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Assets measured at fair value	214,662
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| US Government Agencies Debt Securities [Member]
Assets measured at fair value	1,288	1,572
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Small Business Administration Agency Securities [Member]
Assets measured at fair value	4,515	4,691
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Assets measured at fair value	17,818	19,171
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Collateralized Mortgage Obligations [Member]
Assets measured at fair value	46,336	11,654
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Commercial Paper [Member]
Assets measured at fair value	109,188	69,898
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Corporate Debt Securities [Member]
Assets measured at fair value	33,930	19,083
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Municipal Securities [Member]
Assets measured at fair value	1,587
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Assets measured at fair value	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| US Government Agencies Debt Securities [Member]
Assets measured at fair value	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Small Business Administration Agency Securities [Member]
Assets measured at fair value	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Assets measured at fair value	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Collateralized Mortgage Obligations [Member]
Assets measured at fair value	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Commercial Paper [Member]
Assets measured at fair value	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Corporate Debt Securities [Member]
Assets measured at fair value	0	0
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Municipal Securities [Member]
Assets measured at fair value	0
Fair Value, Nonrecurring [Member]
Assets measured at fair value	293
Fair Value, Nonrecurring [Member] \| Other Real Estate Owned [Member]
Assets measured at fair value	293	293
Fair Value, Nonrecurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Assets measured at fair value	0
Fair Value, Nonrecurring [Member] \| Fair Value, Inputs, Level 1 [Member] \| Other Real Estate Owned [Member]
Assets measured at fair value	0	0
Fair Value, Nonrecurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Assets measured at fair value	0
Fair Value, Nonrecurring [Member] \| Fair Value, Inputs, Level 2 [Member] \| Other Real Estate Owned [Member]
Assets measured at fair value	0	0
Fair Value, Nonrecurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Assets measured at fair value	293
Fair Value, Nonrecurring [Member] \| Fair Value, Inputs, Level 3 [Member] \| Other Real Estate Owned [Member]
Assets measured at fair value	$ 293	$ 293

Note 17 - Fair Value Measurements - Schedule of Hierarchy and Fair Value for Each Major Category of Assets and Liabilities Measured at Fair Value (Details) - USD ($)
$ in Thousands