All assets measured at fair value are categorized in the table below based upon the lowest level of significant input to the valuations. All fair value measurements at the reporting date were on a recurring basis.


September 30, 2026 (In thousands)	Quoted Prices in Active Markets for Identical Instruments (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Recurring fair value measurements
Financial Assets:
U.S. Treasury securities	$	317,844	$	—	$	—	$	317,844

U.S. agency mortgage-backed securities	—		1,125,165		—		1,125,165
Municipal debt securities	—		563,350		—		563,350
Non-U.S. government securities	—		42,169		—		42,169
Corporate debt securities	—		1,933,530		—		1,933,530
Residential and commercial mortgage securities	—		457,485		—		457,485
Asset-backed securities	—		928,298		—		928,298
Money market funds	504,142		—		—		504,142
Total assets at fair value (1) (2)	$	821,986	$	5,049,997	$	—	$	5,871,983


December 31, 2025 (In thousands)	Quoted Prices in Active Markets for Identical Instruments (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Recurring fair value measurements
Financial Assets:
U.S. Treasury securities	$	369,712	$	—	$	—	$	369,712

U.S. agency mortgage-backed securities	—		1,174,895		—		1,174,895
Municipal debt securities	—		610,411		—		610,411
Non-U.S. government securities	—		56,024		—		56,024
Corporate debt securities	—		1,980,080		—		1,980,080
Residential and commercial mortgage securities	—		464,105		—		464,105
Asset-backed securities	—		800,366		—		800,366
Money market funds	648,492		—		—		648,492
Total assets at fair value (1) (2)	$	1,018,204	$	5,085,881	$	—	$	6,104,085

(1)Does not include the fair value of embedded derivatives, which we have accounted for separately as freestanding derivatives and included in other assets or other accrued liabilities in our condensed consolidated balance sheet. See Note 4 for more information.

(2)Does not include certain other invested assets that are measured at fair value using the net asset value per share (or its equivalent) as a practical expedient, as applicable accounting standards do not provide for classification within the fair value hierarchy.