Commitments and Contingencies - (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2034	Dec. 31, 2021	Dec. 31, 2020
Investments in Affordable Housing Limited Entities	$ 92,700,000	$ 50,900,000
Affordable Housing Tax Credits and Other Tax Benefits, Amount	5,700,000	2,400,000	$ 2,900,000
Amortization Method Qualified Affordable Housing Project Investments, Amortization	5,000,000.0	3,100,000	2,200,000
Qualified Affordable Housing Project Investments, Commitment	50,700,000	31,500,000
Impairment losses on LIHTC investments	0	0	0
Carrying value of NMTC	25,400,000	25,700,000
Investment income	701,000	$ 708,000	$ 735,000
Scenario, Forecast [Member]
Qualified Affordable Housing Project Investments, Future Commitment				$ 7,300,000	$ 36,400,000	$ 7,000,000.0
Twenty Twenty [Member] | Subsidiaries [Member] | Investment Tax Credit Carryforward [Member]
Gross tax credits related to the Company's CDEs	$ 9,800,000