Note 5 - Fair Value of Financial Instruments - Assets Measured at Fair Value by Hierarchy Level (Details) - USD ($)	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2021	Dec. 31, 2020
Fair Value by Hierarchy Level [Line Items]
Less: loaned securities	$ 135,058,000	$ 135,058,000	$ 57,499,000
Other Investments	3,899,000	3,899,000	4,973,000
Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	6,657,588,000	6,657,588,000	6,786,469,000
Derivative, Fair Value, Net	5,499,000	5,499,000	5,513,000
Assets, Fair Value Disclosure	6,798,145,000	6,798,145,000	6,849,481,000
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	826,857,000	826,857,000	551,695,000
Derivative, Fair Value, Net	0	0	0
Assets, Fair Value Disclosure	875,435,000	875,435,000	577,870,000
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	5,827,731,000	5,827,731,000	6,231,774,000
Derivative, Fair Value, Net	0	0	0
Assets, Fair Value Disclosure	5,914,211,000	5,914,211,000	6,263,098,000
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	3,000,000	3,000,000	3,000,000
Derivative, Fair Value, Net	5,499,000	5,499,000	5,513,000
Assets, Fair Value Disclosure	8,499,000	8,499,000	8,513,000
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
Securities Financing Transaction, Fair Value | Fair Value, Measurements, Recurring | U.S. government and agencies securities
Fair Value by Hierarchy Level [Line Items]
Less: loaned securities	19,830,000	19,830,000	4,876,000
Securities Financing Transaction, Fair Value | Fair Value, Measurements, Recurring | Corporate bonds and notes
Fair Value by Hierarchy Level [Line Items]
Less: loaned securities	86,480,000	86,480,000	31,324,000
Securities Financing Transaction, Fair Value | Fair Value, Measurements, Recurring | Equity securities
Fair Value by Hierarchy Level [Line Items]
Less: loaned securities	28,748,000	28,748,000	21,299,000
Securities Financing Transaction, Fair Value | Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | U.S. government and agencies securities
Fair Value by Hierarchy Level [Line Items]
Less: loaned securities	19,830,000	19,830,000	4,876,000
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]
Less: loaned securities	0	0	0
Securities Financing Transaction, Fair Value | Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | Equity securities
Fair Value by Hierarchy Level [Line Items]
Less: loaned securities	28,748,000	28,748,000	21,299,000
Securities Financing Transaction, Fair Value | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | U.S. government and agencies securities
Fair Value by Hierarchy Level [Line Items]
Less: loaned securities	0	0	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]
Less: loaned securities	86,480,000	86,480,000	31,324,000
Securities Financing Transaction, Fair Value | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Equity securities
Fair Value by Hierarchy Level [Line Items]
Less: loaned securities	0	0	0
Securities Financing Transaction, Fair Value | Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | U.S. government and agencies securities
Fair Value by Hierarchy Level [Line Items]
Less: loaned securities	0	0	0
Securities Financing Transaction, Fair Value | Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Corporate bonds and notes
Fair Value by Hierarchy Level [Line Items]
Less: loaned securities	0	0	0
Securities Financing Transaction, Fair Value | Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Equity securities
Fair Value by Hierarchy Level [Line Items]
Less: loaned securities	0	0	0
Fixed-maturities available for sale | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	5,580,212,000	5,580,212,000	5,723,340,000
Fixed-maturities available for sale | Fair Value, Measurements, Recurring | U.S. government and agencies securities
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	255,158,000	255,158,000	169,223,000
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	161,011,000	161,011,000	165,271,000
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	2,936,922,000	2,936,922,000	3,047,189,000
Fixed-maturities available for sale | Fair Value, Measurements, Recurring | RMBS
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	713,106,000	713,106,000	833,939,000
Fixed-maturities available for sale | Fair Value, Measurements, Recurring | CMBS
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	706,641,000	706,641,000	681,265,000
Fixed-maturities available for sale | Fair Value, Measurements, Recurring | CLO
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	559,320,000	559,320,000	568,558,000
Fixed-maturities available for sale | Fair Value, Measurements, Recurring | Other ABS
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	195,019,000	195,019,000	252,457,000
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	5,344,000	5,344,000	5,438,000
Fixed-maturities available for sale | Fair Value, Measurements, Recurring | Mortgage insurance-linked notes
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	47,691,000	47,691,000
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	225,540,000	225,540,000	140,034,000
Fixed-maturities available for sale | Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | U.S. government and agencies securities
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	225,540,000	225,540,000	140,034,000
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 | CLO
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 1 | Fair Value, Measurements, Recurring | Mortgage insurance-linked notes
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	5,354,672,000	5,354,672,000	5,583,306,000
Fixed-maturities available for sale | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | U.S. government and agencies securities
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	29,618,000	29,618,000	29,189,000
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	161,011,000	161,011,000	165,271,000
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	2,936,922,000	2,936,922,000	3,047,189,000
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	713,106,000	713,106,000	833,939,000
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	706,641,000	706,641,000	681,265,000
Fixed-maturities available for sale | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | CLO
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	559,320,000	559,320,000	568,558,000
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	195,019,000	195,019,000	252,457,000
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	5,344,000	5,344,000	5,438,000
Fixed-maturities available for sale | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Mortgage insurance-linked notes
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	47,691,000	47,691,000
Fixed-maturities available for sale | Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	0	0	0
Fixed-maturities available for sale | Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | U.S. government and agencies 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 3 | 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 3 | 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 3 | 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 3 | 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 3 | Fair Value, Measurements, Recurring | CLO
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	0	0	0
Fixed-maturities available for sale | Fair Value, Inputs, Level 3 | 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 3 | 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 3 | Fair Value, Measurements, Recurring | Mortgage insurance-linked notes
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	0	0
Trading Securities | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	263,363,000	263,363,000	290,885,000
Trading Securities | Fair Value, Measurements, Recurring | State and municipal obligations
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	99,329,000	99,329,000	120,449,000
Trading Securities | Fair Value, Measurements, Recurring | Corporate bonds and notes
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	120,298,000	120,298,000	123,142,000
Trading Securities | Fair Value, Measurements, Recurring | RMBS
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	10,147,000	10,147,000	13,000,000
Trading Securities | Fair Value, Measurements, Recurring | CMBS
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	33,589,000	33,589,000	34,294,000
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	263,363,000	263,363,000	290,885,000
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	99,329,000	99,329,000	120,449,000
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	120,298,000	120,298,000	123,142,000
Trading Securities | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | RMBS
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	10,147,000	10,147,000	13,000,000
Trading Securities | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | CMBS
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	33,589,000	33,589,000	34,294,000
Trading Securities | Fair Value, Inputs, Level 3 | 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 3 | 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 3 | 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 3 | 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 3 | Fair Value, Measurements, Recurring | CMBS
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	0	0	0
Equity securities | Fair Value, Measurements, Recurring | Equity securities
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	193,498,000	193,498,000	151,240,000
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	185,214,000	185,214,000	142,761,000
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	8,284,000	8,284,000	8,479,000
Equity securities | Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Equity securities
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	0	0	0
Short-term investments | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	617,515,000	617,515,000	618,004,000
Short-term investments | Fair Value, Measurements, Recurring | U.S. government and agencies securities
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	84,823,000	84,823,000
Short-term investments | Fair Value, Measurements, Recurring | State and municipal obligations
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	12,470,000	12,470,000	21,819,000
Short-term investments | Fair Value, Measurements, Recurring | Money market instruments
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	331,280,000	331,280,000	268,900,000
Short-term investments | Fair Value, Measurements, Recurring | Corporate bonds and notes
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	33,080,000	33,080,000	30,495,000
Short-term investments | Fair Value, Measurements, Recurring | CMBS
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	4,748,000	4,748,000
Short-term investments | Fair Value, Measurements, Recurring | Other ABS
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	28,000	28,000	219,000
Short-term investments | Fair Value, Measurements, Recurring | Other investments
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	151,086,000	151,086,000	296,571,000
Short-term investments | Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	416,103,000	416,103,000	268,900,000
Short-term investments | Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | U.S. government and agencies securities
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	84,823,000	84,823,000
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	331,280,000	331,280,000	268,900,000
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 | CMBS
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 ABS
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	0	0
Short-term investments | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	201,412,000	201,412,000	349,104,000
Short-term investments | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | U.S. government and agencies 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	12,470,000	12,470,000	21,819,000
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	33,080,000	33,080,000	30,495,000
Short-term investments | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | CMBS
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	4,748,000	4,748,000
Short-term investments | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Other ABS
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	28,000	28,000	219,000
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	151,086,000	151,086,000	296,571,000
Short-term investments | Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	0	0	0
Short-term investments | Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | U.S. government and agencies securities
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	0	0
Short-term investments | Fair Value, Inputs, Level 3 | 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 3 | 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 3 | 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 3 | Fair Value, Measurements, Recurring | CMBS
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	0	0
Short-term investments | Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Other ABS
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	0	0	0
Short-term investments | Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Other investments
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	0	0	0
Other investments | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	3,000,000	3,000,000	3,000,000
Other investments | Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	0	0	0
Other investments | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	0	0	0
Other investments | Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring
Fair Value by Hierarchy Level [Line Items]
Total Investments at Fair Value	3,000,000	3,000,000	3,000,000
Partnership investment | Investments Measured at NAV
Fair Value by Hierarchy Level [Line Items]
Other Investments	$ 900,000	$ 900,000	$ 2,000,000