Investments - Net Investment Income - Insurance - Components of Investment Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Schedule of Investments [Line Items]
Net investment income	$ 12,219	$ 17,896	$ 9,916
Other revenue	76,185	73,407	51,910
Vessel related revenue	300,223	258,563	163,557
Vessel related revenue
Schedule of Investments [Line Items]
Vessel related revenue	30,144	35,562	22,697
Insurance
Schedule of Investments [Line Items]
Subtotal	18,786	21,102	14,221
Less: investment expenses	6,567	3,206	4,305
Net investment income	12,219	17,896	9,916
Insurance | AFS securities
Schedule of Investments [Line Items]
Investment income, gross	11,262	7,153	7,685
Insurance | Loans, at fair value
Schedule of Investments [Line Items]
Investment income, gross	780	802	801
Insurance | Other investments
Schedule of Investments [Line Items]
Investment income, gross	5,346	5,792	4,253
Insurance | Dividends from equity securities
Schedule of Investments [Line Items]
Investment income, gross	1,398	7,355	1,482
Mortgage
Schedule of Investments [Line Items]
Other revenue	53,660	64,580	48,747
Mortgage | Loans, at fair value
Schedule of Investments [Line Items]
Other revenue	5,384	7,184	5,617
Mortgage | Loans, at fair value | Loan fee income
Schedule of Investments [Line Items]
Other revenue	18,132	21,834	17,900
Mortgage | Dividends from equity securities
Schedule of Investments [Line Items]
Other revenue	$ 0	$ 0	$ 2,533