Discontinued Operations Discontinued Operations Assets and Liabilities Table (Details) - Oppenheimer Multi Family Housing And Healthcare Finance [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disposal Group, Including Discontinued Operation, Interest Income	$ 8	$ 943	$ 1,999
Disposal Group, Including Discontinued Operation, Principal Transactions	0	(9,022)	5,323
Disposal Group, including discontinued operations, Gain on Sale of Assets	0	16,475	0
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal	2,165	16,917	23,262
Disposal Group, Including Discontinued Operation, Revenue	2,173	25,313	30,584
Disposal Group, Including Discontinued Operation, Compensation and Related Expenses	18	4,311	12,406
Disposal Group, Including Discontinued Operation, Communications and Technology	27	221	361
Disposal Group, Including Discontinued Operation, Occupancy and Equipment	0	415	302
Disposal Group, Including Discontinued Operation, Interest Expense	12	408	994
Disposal Group, Including Discontinued Operation, Other Expense	45	2,619	7,382
Disposal Group, Including Discontinued Operation, Operating Expense	102	7,974	21,445
Disposal Group, Including Discontinued Operation, Gross Profit (Loss)	2,071	17,339	9,139
Income (Loss) from Discontinued Operations, before tax, Attributable to Noncontrolling Interest	338	2,830	1,491
Disposal Group, Including Discontinued Operation, Communications and Technology	5,721	(14,097)	3,322
Cash Provided by (Used in) Investing Activities, Discontinued Operations	0	45,448	0
Cash Provided by (Used in) Financing Activities, Discontinued Operations	(20,035)	(35,421)	(249)
Net Cash Provided by (Used in) Discontinued Operations	$ (14,314)	$ (4,070)	$ 3,073