Investments - Debt and Short-term Investments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Investments
Other investments	$ 59,273		$ 59,081
Investment in unconsolidated investees	66,134		56,966
Cash and Short-term Investments
Cash	44,557		36,424
Short-term investments	147,186		134,923
Other Unconsolidated Investees | Maximum
Investments
Investment in unconsolidated investees	1,000
Prime Holdings Insurance Services, Inc. (Prime)
Investments
Investment in unconsolidated investees	66,000
FHLBC
Investments
Investments pledged as collateral	$ 57,000
Investment in federal home loan bank stock	us-gaap:AssetPledgedAsCollateralMember
Federal home loan bank borrowings fair value disclosure	$ 50,000
Investment In Low Income Housing Tax Credit Partnerships (LIHTC)
Investments
Other investments	9,000		10,000
Amortization on low income housing investments	1,000	$ 1,000
Total tax benefit on investments in tax credit partnership	1,000	1,000
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	12,000		13,000
Amortization on qualifying equity investments	1,000	1,000
Total tax benefit on investments in tax credit partnership	1,000	$ 1,000
Investment in Private Funds
Investments
Other investments	27,000		$ 28,000
Fair value investments entities that calculate net asset value per share, unfunded commitments	$ 4,000