Investments - Debt and Short-term Investments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Nov. 12, 2024
Investments
Other investments	$ 57,939	$ 59,081
Fixed maturities and short-term investments on deposit with either regulatory authorities or banks	93,000
FHLBC
Investments
Investments pledged as collateral	$ 53,000
Investment in federal home loan bank stock	us-gaap:AssetPledgedAsCollateralMember
Amount borrowed from FHLB	$ 50,000			$ 50,000
Investment In Low Income Housing Tax Credit Partnerships (LIHTC)
Investments
Other investments	7,000	10,000
Amortization on tax credit partnership investments	$ 3,000	$ 3,000	$ 3,000
Amortization of tax credit partnerships, Statement of Income	Income tax expense	Income tax expense	Income tax expense
Amortization of tax credit partnerships, Statement of Cash Flows	Net earnings	Net earnings	Net earnings
Total tax benefit on investments in tax credit partnership	$ 3,000	$ 3,000	$ 3,000
Investment In Low Income Housing Tax Credit Partnerships (LIHTC) | Maximum
Investments
Qualified affordable housing project investments, unfunded commitment	1,000
Historic tax credit partnerships (HTC)
Investments
Other investments	15,000	13,000
Amortization on tax credit partnership investments	$ 4,000	$ 4,000
Amortization of tax credit partnerships, Statement of Income	Income tax expense	Income tax expense
Amortization of tax credit partnerships, Statement of Cash Flows	Net earnings	Net earnings
Total tax benefit on investments in tax credit partnership	$ 6,000	$ 6,000	$ 5,000
Investment in Private Funds
Investments
Other investments	24,000	$ 28,000
Fair value investments entities that calculate net asset value per share, unfunded commitments	$ 4,000