Accrued Expenses and Other Current Liabilities - Summary of Accrued Expenses and Other Current Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Accounts Payable Accrued Liabilities And Other Current Liabilities [Line Items]
Accrued interest on convertible notes	$ 11,875	$ 5,938
Accrued payroll and employment related withholding taxes	10,709	24,765
Other accrued expenses and current liabilities	8,031	17,032
Accrued interest on Senior Facility	422
Accrued legal and professional fees	364	1,174
Contingent consideration for acquisitions		420
Total accrued expenses and other current liabilities	32,526	50,829
ABG [Member]
Accounts Payable Accrued Liabilities And Other Current Liabilities [Line Items]
ABG finance liability - current	$ 1,125	$ 1,500