Investments - Unrealized Gains or (Losses) Included in Other Comprehensive Income (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Changes in Unrealized Gains (Losses) included in Other Comprehensive Income for Assets Held at the End of the Period	$ (100,457)	$ 1,102
Asset- backed Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Changes in Unrealized Gains (Losses) included in Other Comprehensive Income for Assets Held at the End of the Period	0	63
Collateralized debt obligations
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Changes in Unrealized Gains (Losses) included in Other Comprehensive Income for Assets Held at the End of the Period	(11,098)	13,528
Corporates
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Changes in Unrealized Gains (Losses) included in Other Comprehensive Income for Assets Held at the End of the Period	$ (89,359)	$ (12,489)