Note 11 - Borrowings and Financing Activities - Schedule of Debt (Details) - USD ($) $ in Thousands	Jun. 30, 2020	May 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Advances from Federal Home Loan Banks	$ 175,122		$ 134,875
Senior Notes
Debt Instrument [Line Items]
Senior Notes	1,403,857		887,110
Senior Notes \| Senior Notes Due 2024
Debt Instrument [Line Items]
Senior Notes	444,972		444,445
Senior Notes \| Senior Notes Due 2025
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		6.625%
Senior Notes	515,794		0
Senior Notes \| Senior Notes Due 2027
Debt Instrument [Line Items]
Senior Notes	443,091		442,665
FHLB Advances
Debt Instrument [Line Items]
Long-term Debt, Maturities, Repayments of Principal, Remainder of Fiscal Year	86,264
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months	30,000		79,002
Long-term Debt, Maturities, Repayments of Principal in Year Two	16,925		19,000
Long-term Debt, Maturities, Repayments of Principal in Year Three	21,995		11,925
Long-term Debt, Maturities, Repayments of Principal in Year Four	9,954		14,994
Long-term Debt, Maturities, Repayments of Principal in Year Five	9,984		9,954
Long-term Debt, Maturities, Repayments of Principal after Year Five			0
Advances from Federal Home Loan Banks	$ 175,122		$ 134,875

Amount of borrowings as of the balance sheet date from the Federal Home Loan Bank, which are primarily used to cover shortages in the required reserve balance and liquidity shortages.

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Contractual interest rate for funds borrowed, under the debt agreement.

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