Notes Payable to Related Parties - Schedule of Notes Payable to Related Parties (Parenthetical) (Detail) - Notes Payable to Related Parties [Member]	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
0% Promissory Notes Due 3/31/19 [Member]
Notes Payable to Related Parties [Line Items]
Notes payable, interest rate	0.00%	0.00%
Notes payable, maturity date	Mar. 31, 2019	Mar. 31, 2019
8% Secured Promissory Notes Due 3/31/19 [Member]
Notes Payable to Related Parties [Line Items]
Notes payable, interest rate	8.00%	8.00%
Notes payable, maturity date	Mar. 31, 2019	Mar. 31, 2019
8% Promissory Notes Due 3/31/19 [Member]
Notes Payable to Related Parties [Line Items]
Notes payable, interest rate	8.00%	8.00%
Notes payable, maturity date	Mar. 31, 2019	Mar. 31, 2019
Promissory notes due 10/1/18 [Member]
Notes Payable to Related Parties [Line Items]
Notes payable, maturity date	Oct. 01, 2018	Oct. 01, 2018