Investments - Debt and Short-term Investments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Investment Holdings [Line Items]
Other investments	$ 64,134		$ 47,922
Investment in federal home loan bank stock	us-gaap:AssetPledgedAsCollateralMember		us-gaap:AssetPledgedAsCollateralMember
Cash and Short-term Investments
Investment in unconsolidated investees	$ 52,398		$ 58,275
Cash	22,769		22,818
Short-term investments	116,202		36,229
Prime Holdings Insurance Services, Inc. (Prime)
Cash and Short-term Investments
Investment in unconsolidated investees	52,000
Other Unconsolidated Investees | Maximum
Cash and Short-term Investments
Investment in unconsolidated investees	1,000
FHLBC
Investment Holdings [Line Items]
Investments pledged as collateral	59,000
Federal home loan bank borrowings fair value disclosure	50,000
Investment In Low Income Housing Tax Credit Partnerships (LIHTC)
Investment Holdings [Line Items]
Other investments	13,000		13,000
Total tax benefit on investments in housing tax credit partnership	800	$ 900
Qualified affordable housing project investments, unfunded commitment	1,000
Historic tax credit partnerships (HTC)
Investment Holdings [Line Items]
Other investments	16,000
Total tax benefit on investments in housing tax credit partnership	1,400	$ 1,300
Equity investments in tax credit structures, unfunded commitment	7,000
Cash and Short-term Investments
Investment in unconsolidated investees			11,000
Investment in Private Funds
Investment Holdings [Line Items]
Other investments	28,000		$ 28,000
Fair value investments entities that calculate net asset value per share, unfunded commitments	$ 5,000