Class A Redeemable Convertible Preferred Stock - Schedule of Redemption Discounts (Detail) - Series A Redeemable Convertible Preferred Stock [Member]		12 Months Ended
	Dec. 22, 2016	Dec. 31, 2016
Temporary Equity [Line Items]
Redemption Discount	9.0909%
Commencing on the Original Issue Date and Ending on the 1st Anniversary of Original Issue Date [Member]
Temporary Equity [Line Items]
Redemption Discount		9.0909%
Commencing on the Day After the 1st Anniversary of the Original Issue Date and Ending on the 2nd Anniversary of the Original Issue Date [Member]
Temporary Equity [Line Items]
Redemption Discount		6.8182%
Commencing on the Day After the 2nd Anniversary of the Original Issue Date and Ending on the 3rd Anniversary of the Original Issue Date [Member]
Temporary Equity [Line Items]
Redemption Discount		4.5455%
Commencing on the Day After the 3rd Anniversary of the Original Issue Date and Ending on the 4th Anniversary of the Original Issue Date [Member]
Temporary Equity [Line Items]
Redemption Discount		2.2727%