Investments in Affiliates and Related Transactions - Note Receivable (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Schedule of Equity Method Investments [Line Items]
Modification to liquidation preference	$ 24,000
Movement in Financing Receivable [Roll Forward]
Impairment, activity	(18,225)	$ 0	$ (18,225)	$ 0
Variable Interest Entity, Primary Beneficiary | Sequential Technology International, LLC
Movement in Financing Receivable [Roll Forward]
Seller Note, beginning balance			83,000
Impairment, beginning balance			(14,562)
Unamortized Discount, beginning balance			(12,163)
Loan Accrued Interest, beginning balance			11,096
Distribution Note, beginning balance			6,187
Distribution interest, beginning balance			426
Total, beginning balance			73,984
Seller Note, activity			0
Impairment, activity			(18,225)
Unamortized Discount, activity			438
Loan Accrued Interest, activity			6,103
Distribution Note, activity			3,293
Distribution interest, activity			496
Total, activity			(7,895)
Seller Note, ending balance	83,000		83,000
Impairment, ending balance	(32,787)		(32,787)
Unamortized Discount, ending balance	(11,725)		(11,725)
Loan Accrued Interest, ending balance	17,199		17,199
Distribution Note, ending balance	9,480		9,480
Distribution interest, ending balance	922		922
Total, ending balance	66,089		66,089
Sequential Technology International Holdings, LLC | Goldman Sachs Bank USA | Discontinued Operations, Disposed of by Sale | BPO Divestiture | Indirect Guarantee of Indebtedness | Sequential Technology International, LLC
Schedule of Equity Method Investments [Line Items]
Reduction in equity investment	$ 3,300		$ 3,300