At-The-Market Offering and Firm Commitment Offering - Additional Information (Detail) - USD ($)			9 Months Ended
	Sep. 04, 2019	Aug. 12, 2019	Sep. 30, 2019	Dec. 28, 2018
Stockholders Equity Common Stock [Line Items]
Total shares of common stock sold (in shares)			33,084,151
Stifel, Nicolaus & Company, Incorporated
Stockholders Equity Common Stock [Line Items]
Total shares of common stock sold (in shares)			0
Stifel, Nicolaus & Company, Incorporated | Maximum
Stockholders Equity Common Stock [Line Items]
Sale of common stock in an at-the-market offering				$ 75,000,000.0
2019 ATM Offering
Stockholders Equity Common Stock [Line Items]
Sale of common stock in an at-the-market offering		$ 25,000,000.0
Total shares of common stock sold (in shares)			5,084,151
Percentage of commission paid		3.00%
Firm Commitment Offering
Stockholders Equity Common Stock [Line Items]
Total shares of common stock sold (in shares)			28,000,000
Public Stock Offering | Firm Commitment Offering
Stockholders Equity Common Stock [Line Items]
Number of shares issued (in shares)	28,000,000
Over-Allotment Option | Firm Commitment Offering
Stockholders Equity Common Stock [Line Items]
Number of shares issued (in shares)	4,200,000