Separate Accounts (Separate Account Assets) (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Dec. 31, 2024
Fair Value, Separate Account Investment [Line Items]
Separate account assets	$ 113,586,513	$ 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	18,498	15,548
Obligations of U.S. states and their political subdivisions authorities
Fair Value, Separate Account Investment [Line Items]
Separate account assets	140	115
U.S. corporate securities
Fair Value, Separate Account Investment [Line Items]
Separate account assets	28,128	24,458
Foreign corporate securities
Fair Value, Separate Account Investment [Line Items]
Separate account assets	3,052	3,158
Asset-backed securities
Fair Value, Separate Account Investment [Line Items]
Separate account assets	1,263	1,099
Mortgage-backed securities
Fair Value, Separate Account Investment [Line Items]
Separate account assets	129	82
Equity
Fair Value, Separate Account Investment [Line Items]
Separate account assets	69,189,973	73,226,610
Fixed Income
Fair Value, Separate Account Investment [Line Items]
Separate account assets	32,508,482	33,828,097
Other
Fair Value, Separate Account Investment [Line Items]
Separate account assets	4,851,887	4,431,975
Equity securities
Fair Value, Separate Account Investment [Line Items]
Separate account assets	150,205	126,792
Other invested assets
Fair Value, Separate Account Investment [Line Items]
Separate account assets	6,805,838	6,444,077
Short-term investments
Fair Value, Separate Account Investment [Line Items]
Separate account assets	1,449	2,559
Cash and cash equivalents
Fair Value, Separate Account Investment [Line Items]
Separate account assets	$ 27,469	$ 38,686