Note 4 - Fair Value of Financial Instruments Assets Measured at Fair Value by Hierarchy Level (Details) - USD ($) | 3 Months Ended | 6 Months Ended | 12 Months Ended |
Jun. 30, 2020 | Jun. 30, 2020 | Dec. 31, 2019 |
Fair Value by Hierarchy Level [Line Items] | | | | | | | |
Other Investments | | $ 4,047,000 | | $ 4,047,000 | | $ 4,072,000 | |
Loaned securities | | 16,332,000 | | 16,332,000 | | 66,442,000 | |
Investments Measured at NAV | | | | | | | |
Fair Value by Hierarchy Level [Line Items] | | | | | | | |
Other Investments | | 2,500,000 | | 2,500,000 | | | |
Fair Value, Measurements, Recurring | | | | | | | |
Fair Value by Hierarchy Level [Line Items] | | | | | | | |
Total Investments at Fair Value | | 6,427,303,000 | [1] | 6,427,303,000 | [1] | 5,654,675,000 | [2] |
Assets, Fair Value Disclosure | | 6,443,635,000 | [1] | 6,443,635,000 | [1] | 5,721,117,000 | [2] |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net | | 0 | | 0 | | 0 | |
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Transfers, Net | | 0 | | 0 | | 0 | |
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | | | | | | | |
Fair Value by Hierarchy Level [Line Items] | | | | | | | |
Total Investments at Fair Value | | 638,313,000 | [1] | 638,313,000 | [1] | 597,506,000 | [2] |
Assets, Fair Value Disclosure | | 652,526,000 | [1] | 652,526,000 | [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 | | 5,788,990,000 | [1] | 5,788,990,000 | [1] | 5,057,169,000 | [2] |
Assets, Fair Value Disclosure | | 5,791,109,000 | [1] | 5,791,109,000 | [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 | | 7,600,000 | | 7,600,000 | | 400,000 | |
Securities Financing Transaction, Fair Value | Fair Value, Measurements, Recurring | US government and agency securities | | | | | | | |
Fair Value by Hierarchy Level [Line Items] | | | | | | | |
Loaned securities | [3] | | | | | 35,309,000 | |
Securities Financing Transaction, Fair Value | Fair Value, Measurements, Recurring | Corporate bonds and notes | | | | | | | |
Fair Value by Hierarchy Level [Line Items] | | | | | | | |
Loaned securities | | 2,119,000 | [4] | 2,119,000 | [4] | 3,669,000 | [3] |
Securities Financing Transaction, Fair Value | Fair Value, Measurements, Recurring | Equity securities | | | | | | | |
Fair Value by Hierarchy Level [Line Items] | | | | | | | |
Loaned securities | | 14,213,000 | [4] | 14,213,000 | [4] | 27,464,000 | [3] |
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 | [3] | | | | | 35,309,000 | |
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 | | 0 | [4] | 0 | [4] | 0 | [3] |
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 | | 14,213,000 | [4] | 14,213,000 | [4] | 27,464,000 | [3] |
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] | | | | | 0 | |
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 | | 2,119,000 | [4] | 2,119,000 | [4] | 3,669,000 | [3] |
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 | [4] | 0 | [4] | 0 | [3] |
Fixed-maturities available for sale | Fair Value, Measurements, Recurring | | | | | | | |
Fair Value by Hierarchy Level [Line Items] | | | | | | | |
Total Investments at Fair Value | | 5,070,091,000 | | 5,070,091,000 | | 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 | | 133,043,000 | | 133,043,000 | | 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 | | 123,117,000 | | 123,117,000 | | 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 | | 2,648,456,000 | | 2,648,456,000 | | 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 | | 835,769,000 | | 835,769,000 | | 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 | | 637,491,000 | | 637,491,000 | | 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 | | 686,875,000 | | 686,875,000 | | 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 | | 5,340,000 | | 5,340,000 | | 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 | | 124,600,000 | | 124,600,000 | | 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 | | 124,600,000 | | 124,600,000 | | 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 | | 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 | | 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 | | 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 | | 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 | | 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 | | 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 | | 4,945,491,000 | | 4,945,491,000 | | 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 | | 8,443,000 | | 8,443,000 | | 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 | | 123,117,000 | | 123,117,000 | | 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 | | 2,648,456,000 | | 2,648,456,000 | | 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 | | 835,769,000 | | 835,769,000 | | 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 | | 637,491,000 | | 637,491,000 | | 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 | | 686,875,000 | | 686,875,000 | | 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 | | 5,340,000 | | 5,340,000 | | 5,224,000 | |
Fixed-maturities available for sale | Securities Financing Transaction, Fair Value | Corporate bonds and notes | | | | | | | |
Fair Value by Hierarchy Level [Line Items] | | | | | | | |
Loaned securities | | | | | | 24,013,000 | |
Trading Securities | Fair Value, Measurements, Recurring | | | | | | | |
Fair Value by Hierarchy Level [Line Items] | | | | | | | |
Total Investments at Fair Value | | 297,609,000 | | 297,609,000 | | 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 | | 122,234,000 | | 122,234,000 | | 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 | | 126,000,000 | | 126,000,000 | | 147,232,000 | |
Trading Securities | Fair Value, Measurements, Recurring | RMBS | | | | | | | |
Fair Value by Hierarchy Level [Line Items] | | | | | | | |
Total Investments at Fair Value | | 15,205,000 | | 15,205,000 | | 16,180,000 | |
Trading Securities | Fair Value, Measurements, Recurring | CMBS | | | | | | | |
Fair Value by Hierarchy Level [Line Items] | | | | | | | |
Total Investments at Fair Value | | 34,170,000 | | 34,170,000 | | 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 | | 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 | | 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 | | 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 | | 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 | | 0 | |
Trading Securities | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | | | | | | | |
Fair Value by Hierarchy Level [Line Items] | | | | | | | |
Total Investments at Fair Value | | 297,609,000 | | 297,609,000 | | 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 | | 122,234,000 | | 122,234,000 | | 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 | | 126,000,000 | | 126,000,000 | | 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 | | 15,205,000 | | 15,205,000 | | 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 | | 34,170,000 | | 34,170,000 | | 34,789,000 | |
Equity securities | Fair Value, Measurements, Recurring | Equity securities | | | | | | | |
Fair Value by Hierarchy Level [Line Items] | | | | | | | |
Total Investments at Fair Value | | 104,513,000 | | 104,513,000 | | 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 | | 96,089,000 | | 96,089,000 | | 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 | | 8,424,000 | | 8,424,000 | | 6,212,000 | |
Short-term investments | Fair Value, Measurements, Recurring | | | | | | | |
Fair Value by Hierarchy Level [Line Items] | | | | | | | |
Total Investments at Fair Value | | 955,090,000 | | 955,090,000 | | 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 | | 42,528,000 | | 42,528,000 | | 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 | | 5,397,000 | | 5,397,000 | | 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 | | 375,096,000 | | 375,096,000 | | 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 | | 149,490,000 | | 149,490,000 | | 20,298,000 | |
Short-term investments | Fair Value, Measurements, Recurring | Other investments | | | | | | | |
Fair Value by Hierarchy Level [Line Items] | | | | | | | |
Total Investments at Fair Value | | 382,579,000 | [5] | 382,579,000 | [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 | | 417,624,000 | | 417,624,000 | | 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 | | 42,528,000 | | 42,528,000 | | 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 | | 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 | | 375,096,000 | | 375,096,000 | | 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 | | 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 | [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 | | 537,466,000 | | 537,466,000 | | 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 | | 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 | | 5,397,000 | | 5,397,000 | | 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 | | 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 | | 149,490,000 | | 149,490,000 | | 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 | | 382,579,000 | [5] | 382,579,000 | [5] | 147,007,000 | [6] |
Partnership investment | | | | | | | |
Fair Value by Hierarchy Level [Line Items] | | | | | | | |
Other Investments | | | | | | 2,600,000 | |
Convertible promissory note | | | | | | | |
Fair Value by Hierarchy Level [Line Items] | | | | | | | |
Other Investments | | $ 1,500,000 | | $ 1,500,000 | | $ 1,500,000 | |
| |
[1] | Does not include other invested assets of $2.5 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. | |