Related Party Transactions - Summary of Related Party Costs - Related Party Transactions (Parenthetical) (Detail) - USD ($)	4 Months Ended	12 Months Ended
	Apr. 30, 2018	Dec. 31, 2018	Dec. 31, 2017
Related Party Transaction [Line Items]
Asset management fee waived by advisor	$ 160,000		$ 135,000
Dealer Manager [Member] | Class T Common Stock [Member] | Additional Paid In Capital Selling Commissions [Member]
Related Party Transaction [Line Items]
Monthly stockholder servicing fee accrual description		accrues daily in an amount equal to 1/365th of 1% of the purchase price per share
Dealer Manager [Member] | Class W Common Stock [Member] | Additional Paid In Capital Selling Commissions [Member]
Related Party Transaction [Line Items]
Monthly stockholder servicing fee accrual description		accrues daily in an amount equal to 1/365th of 0.5% of the purchase price per share