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Note 4 - Fair Value of Financial Instruments Assets Measured at Fair Value by Hierarchy Level (Details) - USD ($) | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2020 | Dec. 31, 2019
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Other Investments |  | $ 4,131,000 |  | $ 4,072,000 |
Loaned securities |  | 47,520,000 |  | 66,442,000 |
Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 5,604,496,000 | [1] | 5,654,675,000 | [2]
Assets, Fair Value Disclosure |  | 5,652,016,000 | [1] | 5,721,117,000 | [2]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net |  | 0 |  | 0 |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Transfers, Net |  | 0 |  | 0 |
Fair Value, Measurements, Recurring | Investments Measured at NAV |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Other Investments |  | 2,600,000 |  |  |
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 659,008,000 | [1] | 597,506,000 | [2]
Assets, Fair Value Disclosure |  | 702,744,000 | [1] | 660,279,000 | [2]
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 4,945,488,000 | [1] | 5,057,169,000 | [2]
Assets, Fair Value Disclosure |  | 4,949,272,000 | [1] | 5,060,838,000 | [2]
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Assets, Fair Value Disclosure |  | 0 |  | 400,000 |
Financial Liabilities Fair Value Disclosure |  | 5,600,000 |  | 0 |
Securities Financing Transaction, Fair Value | Fair Value, Measurements, Recurring | US government and agency securities |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Loaned securities |  | 3,784,000 | [3] | 35,309,000 | [4]
Securities Financing Transaction, Fair Value | Fair Value, Measurements, Recurring | Corporate bonds and notes |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Loaned securities | [4] |  |  | 3,669,000 |
Securities Financing Transaction, Fair Value | Fair Value, Measurements, Recurring | Equity securities |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Loaned securities |  | 43,736,000 | [3] | 27,464,000 | [4]
Securities Financing Transaction, Fair Value | Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | US government and agency securities |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Loaned securities |  | 0 | [3] | 35,309,000 | [4]
Securities Financing Transaction, Fair Value | Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | Corporate bonds and notes |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Loaned securities | [4] |  |  | 0 |
Securities Financing Transaction, Fair Value | Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | Equity securities |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Loaned securities |  | 43,736,000 | [3] | 27,464,000 | [4]
Securities Financing Transaction, Fair Value | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | US government and agency securities |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Loaned securities |  | 3,784,000 | [3] | 0 | [4]
Securities Financing Transaction, Fair Value | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Corporate bonds and notes |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Loaned securities | [4] |  |  | 3,669,000 |
Securities Financing Transaction, Fair Value | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Equity securities |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Loaned securities |  | 0 | [3] | 0 | [4]
Fixed-maturities available for sale | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 4,603,613,000 |  | 4,688,911,000 |
Fixed-maturities available for sale | Fair Value, Measurements, Recurring | US government and agency securities |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 159,240,000 |  | 179,584,000 |
Fixed-maturities available for sale | Fair Value, Measurements, Recurring | State and municipal obligations |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 116,975,000 |  | 119,994,000 |
Fixed-maturities available for sale | Fair Value, Measurements, Recurring | Corporate bonds and notes |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 2,265,066,000 |  | 2,237,611,000 |
Fixed-maturities available for sale | Fair Value, Measurements, Recurring | RMBS |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 779,590,000 |  | 779,354,000 |
Fixed-maturities available for sale | Fair Value, Measurements, Recurring | CMBS |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 610,877,000 |  | 608,015,000 |
Fixed-maturities available for sale | Fair Value, Measurements, Recurring | Other ABS |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 666,918,000 |  | 759,129,000 |
Fixed-maturities available for sale | Fair Value, Measurements, Recurring | Foreign government and agency securities |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 4,947,000 |  | 5,224,000 |
Fixed-maturities available for sale | Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 155,498,000 |  | 143,884,000 |
Fixed-maturities available for sale | Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | US government and agency securities |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 155,498,000 |  | 143,884,000 |
Fixed-maturities available for sale | Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | State and municipal obligations |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 0 |  | 0 |
Fixed-maturities available for sale | Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | Corporate bonds and notes |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 0 |  | 0 |
Fixed-maturities available for sale | Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | RMBS |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 0 |  | 0 |
Fixed-maturities available for sale | Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | CMBS |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 0 |  | 0 |
Fixed-maturities available for sale | Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | Other ABS |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 0 |  | 0 |
Fixed-maturities available for sale | Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | Foreign government and agency securities |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 0 |  | 0 |
Fixed-maturities available for sale | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 4,448,115,000 |  | 4,545,027,000 |
Fixed-maturities available for sale | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | US government and agency securities |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 3,742,000 |  | 35,700,000 |
Fixed-maturities available for sale | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | State and municipal obligations |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 116,975,000 |  | 119,994,000 |
Fixed-maturities available for sale | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Corporate bonds and notes |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 2,265,066,000 |  | 2,237,611,000 |
Fixed-maturities available for sale | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | RMBS |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 779,590,000 |  | 779,354,000 |
Fixed-maturities available for sale | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | CMBS |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 610,877,000 |  | 608,015,000 |
Fixed-maturities available for sale | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Other ABS |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 666,918,000 |  | 759,129,000 |
Fixed-maturities available for sale | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Foreign government and agency securities |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 4,947,000 |  | 5,224,000 |
Trading Securities | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 287,270,000 |  | 317,150,000 |
Trading Securities | Fair Value, Measurements, Recurring | State and municipal obligations |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 114,511,000 |  | 118,949,000 |
Trading Securities | Fair Value, Measurements, Recurring | Corporate bonds and notes |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 123,461,000 |  | 147,232,000 |
Trading Securities | Fair Value, Measurements, Recurring | RMBS |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 15,573,000 |  | 16,180,000 |
Trading Securities | Fair Value, Measurements, Recurring | CMBS |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 33,725,000 |  | 34,789,000 |
Trading Securities | Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 0 |  | 0 |
Trading Securities | Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | State and municipal obligations |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 0 |  | 0 |
Trading Securities | Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | Corporate bonds and notes |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 0 |  | 0 |
Trading Securities | Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | RMBS |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 0 |  | 0 |
Trading Securities | Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | CMBS |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 0 |  | 0 |
Trading Securities | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 287,270,000 |  | 317,150,000 |
Trading Securities | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | State and municipal obligations |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 114,511,000 |  | 118,949,000 |
Trading Securities | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Corporate bonds and notes |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 123,461,000 |  | 147,232,000 |
Trading Securities | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | RMBS |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 15,573,000 |  | 16,180,000 |
Trading Securities | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | CMBS |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 33,725,000 |  | 34,789,000 |
Equity securities | Fair Value, Measurements, Recurring | Equity securities |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 74,853,000 |  | 130,221,000 |
Equity securities | Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | Equity securities |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 67,086,000 |  | 124,009,000 |
Equity securities | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Equity securities |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 7,767,000 |  | 6,212,000 |
Short-term investments | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 638,760,000 |  | 518,393,000 |
Short-term investments | Fair Value, Measurements, Recurring | US government and agency securities |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 140,667,000 |  | 127,152,000 |
Short-term investments | Fair Value, Measurements, Recurring | State and municipal obligations |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 10,148,000 |  | 21,475,000 |
Short-term investments | Fair Value, Measurements, Recurring | Money market instruments |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 295,757,000 |  | 202,461,000 |
Short-term investments | Fair Value, Measurements, Recurring | Corporate bonds and notes |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 117,836,000 |  | 20,298,000 |
Short-term investments | Fair Value, Measurements, Recurring | Other investments |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 74,352,000 | [5] | 147,007,000 | [6]
Short-term investments | Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 436,424,000 |  | 329,613,000 |
Short-term investments | Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | US government and agency securities |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 140,667,000 |  | 127,152,000 |
Short-term investments | Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | State and municipal obligations |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 0 |  | 0 |
Short-term investments | Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | Money market instruments |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 295,757,000 |  | 202,461,000 |
Short-term investments | Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | Corporate bonds and notes |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 0 |  | 0 |
Short-term investments | Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | Other investments |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 0 | [5] | 0 | [6]
Short-term investments | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 202,336,000 |  | 188,780,000 |
Short-term investments | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | US government and agency securities |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 0 |  | 0 |
Short-term investments | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | State and municipal obligations |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 10,148,000 |  | 21,475,000 |
Short-term investments | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Money market instruments |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 0 |  | 0 |
Short-term investments | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Corporate bonds and notes |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 117,836,000 |  | 20,298,000 |
Short-term investments | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Other investments |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Total Investments at Fair Value |  | 74,352,000 | [5] | 147,007,000 | [6]
Carrying (Reported) Amount, Fair Value Disclosure | Partnership investment |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Other Investments |  |  |  | 2,600,000 |
Carrying (Reported) Amount, Fair Value Disclosure | Convertible promissory note |  |  |  |  |
Fair Value by Hierarchy Level [Line Items] |  |  |  |  |
Other Investments |  | $ 1,500,000 |  | $ 1,500,000 |
[1] | Does not include other invested assets of $2.6 million that are primarily invested in limited partnership investments valued using the net asset value as a practical expedient and $1.5 million invested in a private convertible promissory note.
[2] | Does not include other invested assets of $2.6 million that are primarily invested in limited partnership investments valued using the net asset value as a practical expedient and $1.5 million invested in a private convertible promissory note.
[3] | Securities loaned to third-party borrowers under securities lending agreements are classified as other assets in our condensed consolidated balance sheets. See Note 5 for more information.
[4] | Securities loaned to third-party borrowers under securities lending agreements are classified as other assets in our condensed consolidated balance sheets. See Note 5 for more information.
[5] | Comprising short-term certificates of deposit and commercial paper.
[6] | Comprising short-term certificates of deposit and commercial paper.

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- Definition Fair value of financial obligations, including, but not limited to, debt instruments, derivative liabilities, federal funds purchased and sold under agreements to repurchase, securities loaned or sold under agreements to repurchase, financial instruments sold not yet purchased, guarantees, line of credit, loans and notes payable, servicing liability, and trading liabilities. + References No definition available. + Details
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