v3.24.1.u1
Fair Value Measurements - Unrealized Loss Position (Details)
$ in Thousands
Mar. 31, 2024
USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]  
Unrealized Losses within 12 months, Fair Value $ 2,486,053
Unrealized Losses within 12 months, Unrealized Losses (7,756)
Unrealized Losses 12 months or greater, Fair Value 78,324
Unrealized Losses 12 months or greater, Unrealized Losses (251)
Total, Fair Value 2,564,377
Total, Unrealized Losses (8,007)
U.S. government notes  
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]  
Unrealized Losses within 12 months, Fair Value 730,912
Unrealized Losses within 12 months, Unrealized Losses (2,688)
Unrealized Losses 12 months or greater, Fair Value 0
Unrealized Losses 12 months or greater, Unrealized Losses 0
Total, Fair Value 730,912
Total, Unrealized Losses (2,688)
Corporate bonds  
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]  
Unrealized Losses within 12 months, Fair Value 1,330,835
Unrealized Losses within 12 months, Unrealized Losses (3,944)
Unrealized Losses 12 months or greater, Fair Value 68,345
Unrealized Losses 12 months or greater, Unrealized Losses (198)
Total, Fair Value 1,399,180
Total, Unrealized Losses (4,142)
Agency securities  
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]  
Unrealized Losses within 12 months, Fair Value 424,306
Unrealized Losses within 12 months, Unrealized Losses (1,124)
Unrealized Losses 12 months or greater, Fair Value 9,979
Unrealized Losses 12 months or greater, Unrealized Losses (53)
Total, Fair Value 434,285
Total, Unrealized Losses $ (1,177)