Fixed Assets (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross		$ 58,073	$ 68,851
Less: Accumulated depreciation and amortization		(31,630)	(28,355)
Fixed assets, net		26,443	40,496
Other Depreciation and Amortization		7,400	7,000	$ 7,700
Gain (Loss) on Disposition of Property Plant Equipment		(15,343)	2,346	0
Telephone and computer equipment
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross		3,301	3,465
Computer software
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross		4,214	2,914
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross		2,829	1,423
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross		37,652	36,702
Assets acquired under capital leases-equipment
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross		10,077	6,920
Depreciation		1,600	1,000	1,200
Capital Leases, Lessee Balance Sheet, Assets by Major Class, Accumulated Depreciation		5,000	3,400
Aircraft and related equipment
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross		0	17,369
Gain (Loss) on Disposition of Property Plant Equipment	$ 2,300	1,000
Depreciation		800	1,500	$ 1,700
Other Capitalized Property Plant and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross		$ 0	$ 58