Redeemable Preferred Stock - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands			12 Months Ended
	Nov. 07, 2018	Aug. 30, 2017	Dec. 31, 2018	Dec. 31, 2017
Temporary Equity [Line Items]
Temporary equity, stock issued during period, shares, new issues			150,000	150,000
Temporary equity, par value			$ 0.01	$ 0.01
Proceeds from issuance of redeemable preferred shares				$ 150,000
Convertible Preferred Stock, Redemption Value			$ 300,000
Issuance costs				3,737
Proceeds from issuance of redeemable preferred shares, net of issuance costs				146,300
Embedded derivative liability			$ 3,134	4,685
Adjusted proceeds from issuance of redeemable preferred shares				135,500
Redemption period			8 years
Carrying value of redeemable preferred stock	$ 17,200		$ (17,200)
Preferred stock redemption extended date	Sep. 14, 2025
Accumulated accretion value			9,000
Redeemable preferred stock			144,463	$ 144,694
Convertible Preferred Stock Redemption Period Two [Member]
Temporary Equity [Line Items]
Convertible Preferred Stock, Redemption Value			$ 300,000
Convertible preferred stock, redemption value percent of stated value			200.00%
Convertible preferred stock, total shares issued upon conversion			5,300,000
Series A Redeemable Preferred Stock [Member]
Temporary Equity [Line Items]
Temporary equity, stock issued during period, shares, new issues				140,202
Temporary equity, par value		$ 0.01
Temporary equity, liquidation preference per share		1,000
Temporary equity, conversion price		$ 28.162
Preferred stock, dividend rate, percentage		9.00%
Convertible preferred stock, threshold stock price trigger				$ 84.49
Series B Redeemable Preferred Stock [Member]
Temporary Equity [Line Items]
Temporary equity, stock issued during period, shares, new issues				9,798