Separate Accounts (Separate Account Assets) (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Fair Value, Separate Account Investment [Line Items]
Separate account assets	$ 117,840,155	$ 114,051,246
U.S. Treasury securities and obligations of U.S. government authorities and agencies
Fair Value, Separate Account Investment [Line Items]
Separate account assets	2,948	2,510
U.S. corporate securities
Fair Value, Separate Account Investment [Line Items]
Separate account assets	5,038	8,702
Foreign corporate securities
Fair Value, Separate Account Investment [Line Items]
Separate account assets	1,796	1,420
Mortgage-backed securities
Fair Value, Separate Account Investment [Line Items]
Separate account assets	282	276
Equity
Fair Value, Separate Account Investment [Line Items]
Separate account assets	71,084,752	67,144,660
Fixed Income
Fair Value, Separate Account Investment [Line Items]
Separate account assets	37,875,086	38,109,374
Other
Fair Value, Separate Account Investment [Line Items]
Separate account assets	3,967,348	3,441,016
Equity securities
Fair Value, Separate Account Investment [Line Items]
Separate account assets	83,396	49,260
Other invested assets
Fair Value, Separate Account Investment [Line Items]
Separate account assets	4,805,171	5,262,178
Short-term investments
Fair Value, Separate Account Investment [Line Items]
Separate account assets	1,691	1,237
Cash and cash equivalents
Fair Value, Separate Account Investment [Line Items]
Separate account assets	$ 12,647	$ 30,613