Nature of Business and Summary of Significant Accounting Policies - Summary of Company's Customers Accounts Receivable (Detail) - Customer Concentration Risk			12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accounts Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of amount due from major customers accounts receivable	95.00%	94.00%
Accounts Receivable | Customer A
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of amount due from major customers accounts receivable	42.00%	47.00%
Accounts Receivable | Customer B
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of amount due from major customers accounts receivable	35.00%	22.00%
Accounts Receivable | Customer C
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of amount due from major customers accounts receivable	18.00%	25.00%
Revenue Benchmark
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of amount due from major customers accounts receivable			94.00%	92.00%	92.00%