Income Taxes Summary of Operating Loss Carryforwards (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating Loss Carryforwards [Line Items]
Income Taxes Receivable	$ 0
Accrued Income Taxes	6,300,000
Valuation allowance	2,103,000	$ 2,119,000
Deferred Tax Assets, Gross	136,048,000	188,549,000
Deferred Tax Liabilities, Gross	17,622,000	20,774,000
Deferred Income Tax Expense (Benefit)	41,170,000	(22,594,000)	$ (47,522,000)
Operating Loss Carryforwards	1,800,000
Other	2,696,000	$ 2,238,000
Deferred tax asset, deduction limitation	2,400,000
Internal Revenue Service (IRS) [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	$ 248,400,000
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2036
New York State Division of Taxation and Finance [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	$ 93,400,000
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2036
State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	$ 130,800,000
Operating Loss Carryforwards, Expiration Date	Dec. 31, 2036
Inland Revenue, Hong Kong [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	$ 12,800,000
Luxembourg Reinsurance Companies
Operating Loss Carryforwards [Line Items]
Valuation allowance	146,000,000
Other	146,000,000
Deferred Tax Liabilities, Gross, Current	349,100,000
LaBranche and Co Inc. [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	50,100,000
Deferred tax asset, deduction limitation	$ 6,700,000