XML 101 R84.htm IDEA: XBRL DOCUMENT v3.22.4
Fair Value of Financial Instruments (Details) - USD ($)
$ in Thousands
Dec. 31, 2022
Dec. 31, 2021
Financial Assets:    
Fair Value $ 4,741,625 $ 4,962,887
Recurring    
Financial Assets:    
Total assets at fair value 4,741,625 4,962,887
Recurring | U.S. Treasury securities    
Financial Assets:    
Fair Value 556,438 448,793
Recurring | U.S. agency securities    
Financial Assets:    
Fair Value 49,058 5,504
Recurring | U.S. agency mortgage-backed securities    
Financial Assets:    
Fair Value 783,743 1,008,863
Recurring | Municipal debt securities    
Financial Assets:    
Fair Value 602,690 627,599
Recurring | Non-U.S. government securities    
Financial Assets:    
Fair Value 62,399 79,743
Recurring | Corporate debt securities    
Financial Assets:    
Fair Value 1,414,321 1,455,247
Recurring | Residential and commercial mortgage securities    
Financial Assets:    
Fair Value 511,824 545,423
Recurring | Asset-backed securities    
Financial Assets:    
Fair Value 624,561 581,703
Recurring | Money market funds    
Financial Assets:    
Fair Value 136,591 210,012
Recurring | Quoted Prices in Active  Markets for Identical Instruments (Level 1)    
Financial Assets:    
Total assets at fair value 693,029 658,805
Recurring | Quoted Prices in Active  Markets for Identical Instruments (Level 1) | U.S. Treasury securities    
Financial Assets:    
Fair Value 556,438 448,793
Recurring | Quoted Prices in Active  Markets for Identical Instruments (Level 1) | U.S. agency securities    
Financial Assets:    
Fair Value 0 0
Recurring | Quoted Prices in Active  Markets for Identical Instruments (Level 1) | U.S. agency mortgage-backed securities    
Financial Assets:    
Fair Value 0 0
Recurring | Quoted Prices in Active  Markets for Identical Instruments (Level 1) | Municipal debt securities    
Financial Assets:    
Fair Value 0 0
Recurring | Quoted Prices in Active  Markets for Identical Instruments (Level 1) | Non-U.S. government securities    
Financial Assets:    
Fair Value 0 0
Recurring | Quoted Prices in Active  Markets for Identical Instruments (Level 1) | Corporate debt securities    
Financial Assets:    
Fair Value 0 0
Recurring | Quoted Prices in Active  Markets for Identical Instruments (Level 1) | Residential and commercial mortgage securities    
Financial Assets:    
Fair Value 0 0
Recurring | Quoted Prices in Active  Markets for Identical Instruments (Level 1) | Asset-backed securities    
Financial Assets:    
Fair Value 0 0
Recurring | Quoted Prices in Active  Markets for Identical Instruments (Level 1) | Money market funds    
Financial Assets:    
Fair Value 136,591 210,012
Recurring | Significant Other Observable Inputs (Level 2)    
Financial Assets:    
Total assets at fair value 4,048,596 4,304,082
Recurring | Significant Other Observable Inputs (Level 2) | U.S. Treasury securities    
Financial Assets:    
Fair Value 0 0
Recurring | Significant Other Observable Inputs (Level 2) | U.S. agency securities    
Financial Assets:    
Fair Value 49,058 5,504
Recurring | Significant Other Observable Inputs (Level 2) | U.S. agency mortgage-backed securities    
Financial Assets:    
Fair Value 783,743 1,008,863
Recurring | Significant Other Observable Inputs (Level 2) | Municipal debt securities    
Financial Assets:    
Fair Value 602,690 627,599
Recurring | Significant Other Observable Inputs (Level 2) | Non-U.S. government securities    
Financial Assets:    
Fair Value 62,399 79,743
Recurring | Significant Other Observable Inputs (Level 2) | Corporate debt securities    
Financial Assets:    
Fair Value 1,414,321 1,455,247
Recurring | Significant Other Observable Inputs (Level 2) | Residential and commercial mortgage securities    
Financial Assets:    
Fair Value 511,824 545,423
Recurring | Significant Other Observable Inputs (Level 2) | Asset-backed securities    
Financial Assets:    
Fair Value 624,561 581,703
Recurring | Significant Other Observable Inputs (Level 2) | Money market funds    
Financial Assets:    
Fair Value 0 0
Recurring | Significant Unobservable Inputs (Level 3)    
Financial Assets:    
Total assets at fair value 0 0
Recurring | Significant Unobservable Inputs (Level 3) | U.S. Treasury securities    
Financial Assets:    
Fair Value 0 0
Recurring | Significant Unobservable Inputs (Level 3) | U.S. agency securities    
Financial Assets:    
Fair Value 0 0
Recurring | Significant Unobservable Inputs (Level 3) | U.S. agency mortgage-backed securities    
Financial Assets:    
Fair Value 0 0
Recurring | Significant Unobservable Inputs (Level 3) | Municipal debt securities    
Financial Assets:    
Fair Value 0 0
Recurring | Significant Unobservable Inputs (Level 3) | Non-U.S. government securities    
Financial Assets:    
Fair Value 0 0
Recurring | Significant Unobservable Inputs (Level 3) | Corporate debt securities    
Financial Assets:    
Fair Value 0 0
Recurring | Significant Unobservable Inputs (Level 3) | Residential and commercial mortgage securities    
Financial Assets:    
Fair Value 0 0
Recurring | Significant Unobservable Inputs (Level 3) | Asset-backed securities    
Financial Assets:    
Fair Value 0 0
Recurring | Significant Unobservable Inputs (Level 3) | Money market funds    
Financial Assets:    
Fair Value $ 0 $ 0