Separate Accounts (Separate Account Assets) (Details) - USD ($) $ in Thousands	Jun. 30, 2025	Dec. 31, 2024
Fair Value, Separate Account Investment [Line Items]
Separate account assets	$ 117,646,018	$ 118,143,256
U.S. Treasury securities and obligations of U.S. government authorities and agencies
Fair Value, Separate Account Investment [Line Items]
Separate account assets	18,466	15,548
Obligations of U.S. states and their political subdivisions authorities
Fair Value, Separate Account Investment [Line Items]
Separate account assets	125	115
U.S. corporate securities
Fair Value, Separate Account Investment [Line Items]
Separate account assets	27,807	24,458
Foreign corporate securities
Fair Value, Separate Account Investment [Line Items]
Separate account assets	3,376	3,158
Asset-backed securities
Fair Value, Separate Account Investment [Line Items]
Separate account assets	1,014	1,099
Mortgage-backed securities
Fair Value, Separate Account Investment [Line Items]
Separate account assets	120	82
Equity
Fair Value, Separate Account Investment [Line Items]
Separate account assets	72,667,286	73,226,610
Fixed Income
Fair Value, Separate Account Investment [Line Items]
Separate account assets	32,398,622	33,828,097
Other
Fair Value, Separate Account Investment [Line Items]
Separate account assets	5,169,686	4,431,975
Equity securities
Fair Value, Separate Account Investment [Line Items]
Separate account assets	186,276	126,792
Other invested assets
Fair Value, Separate Account Investment [Line Items]
Separate account assets	7,104,406	6,444,077
Short-term investments
Fair Value, Separate Account Investment [Line Items]
Separate account assets	6,364	2,559
Cash and cash equivalents
Fair Value, Separate Account Investment [Line Items]
Separate account assets	$ 62,470	$ 38,686