Income Taxes Summary of Operating Loss Carryforwards (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating Loss Carryforwards [Line Items]
Income Taxes Receivable	$ 6,500,000
Deferred Tax Assets, Gross	144,056,000	$ 121,569,000
Deferred Tax Liabilities, Gross	59,656,000	19,377,000
Income (Loss) from Continuing Operations before Income Taxes, Domestic	68,900,000	93,000,000	$ 3,900,000
Deferred Tax Assets, Other	3,043,000	2,444,000
Deferred Tax Assets, Valuation Allowance	5,234,000	9,135,000
Deferred Income Tax Expense (Benefit)	13,296,000	18,965,000	41,170,000
Income (Loss) from Continuing Operations before Income Taxes, Foreign	2,200,000	$ 6,000,000.0	$ 3,100,000
Foreign Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforward, Amount	5,600,000
Tax Credit Carryforward, Valuation Allowance	4,200,000
State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	108,800,000
Inland Revenue, Hong Kong [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	12,500,000
New York State Division of Taxation and Finance [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	67,900,000
Internal Revenue Service (IRS) [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	175,100,000
Luxembourg Reinsurance Companies [Member]
Operating Loss Carryforwards [Line Items]
Deferred Tax Assets, Other	258,400,000
Deferred Tax Liabilities, Gross, Current	224,500,000
Deferred Tax Assets, Valuation Allowance	258,400,000
LaBranche and Co Inc. [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	30,300,000
Deferred tax asset, deduction limitation	$ 6,700,000