Separate Accounts (Separate Account Assets) (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Fair Value, Separate Account Investment [Line Items]
Separate account assets	$ 119,980,906	$ 119,188,485
U.S. Treasury securities and obligations of U.S. government authorities and agencies
Fair Value, Separate Account Investment [Line Items]
Separate account assets	4,925	2,954
Obligations of U.S. states and their political subdivisions authorities
Fair Value, Separate Account Investment [Line Items]
Separate account assets	65	0
U.S. corporate securities
Fair Value, Separate Account Investment [Line Items]
Separate account assets	11,788	9,504
Foreign corporate securities
Fair Value, Separate Account Investment [Line Items]
Separate account assets	2,237	1,763
Asset-backed securities
Fair Value, Separate Account Investment [Line Items]
Separate account assets	1,016	0
Mortgage-backed securities
Fair Value, Separate Account Investment [Line Items]
Separate account assets	175	186
Equity
Fair Value, Separate Account Investment [Line Items]
Separate account assets	75,066,834	72,614,821
Fixed Income
Fair Value, Separate Account Investment [Line Items]
Separate account assets	34,707,360	37,065,162
Other
Fair Value, Separate Account Investment [Line Items]
Separate account assets	4,324,051	4,101,661
Equity securities
Fair Value, Separate Account Investment [Line Items]
Separate account assets	99,581	104,159
Other invested assets
Fair Value, Separate Account Investment [Line Items]
Separate account assets	5,740,307	5,258,900
Short-term investments
Fair Value, Separate Account Investment [Line Items]
Separate account assets	574	2,126
Cash and cash equivalents
Fair Value, Separate Account Investment [Line Items]
Separate account assets	$ 21,993	$ 27,249