Redeemable Preferred Stock - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended	6 Months Ended			7 Months Ended	12 Months Ended
	Nov. 29, 2018	Jun. 30, 2019	Jun. 30, 2019		Jun. 30, 2018	Jun. 30, 2019	Dec. 31, 2018
Temporary Equity [Line Items]
Shares issued			2,000,000		2,000,000
Dividends paid		$ 10.0	$ 20.0	[1]
Redeemable Preferred Stock [Member]
Temporary Equity [Line Items]
Preferred stock dividend rate			12.00%
Accreted value of redeemable preferred stock		$ 1,000.00	$ 1,000.00			$ 1,000.00
Preferred stock dividend rate per quarter			3.00%
Preferred stock applicable dividend rate when prior dividend unpaid			13.00%
Temporary equity, liquidation preference per share		$ 1,200.00	$ 1,200.00			$ 1,200.00
Percentage of share purchase price for redemption in cash			101.00%
Percentage of volume weighted average price of common stock for redemption in shares			96.00%
Period of accretion adjustment to retained earnings deficit			7 years
Expected redemption date			Nov. 29, 2025
Cumulative catch-up adjustment to opening Retained earnings (Accumulated deficit)		$ 4.0	$ 8.0			$ 9.0
Redeemable preferred stock		257.0	257.0			257.0
Adjusted accretion and PIK on redeemable preferred stock			$ 20.0
Dividends paid							$ 3.0
Number of days to purchase shares of common stock at price per share less than the fair market value per share			60 days
Redeemable Preferred Stock [Member] | Prior to January 1, 2020
Temporary Equity [Line Items]
Multiple of invested capital as minimum return			1.2
Redeemable Preferred Stock [Member] | On or After January 1, 2020 But Prior to January 1, 2022
Temporary Equity [Line Items]
Multiple of invested capital as minimum return			1.25
Redeemable Preferred Stock [Member] | On or After January 1, 2022 But Prior to January 1, 2023
Temporary Equity [Line Items]
Multiple of invested capital as minimum return			1.20
Redeemable Preferred Stock [Member] | On or After January 1, 2023 But Prior to January 1, 2025
Temporary Equity [Line Items]
Multiple of invested capital as minimum return			1.15
Redeemable Preferred Stock [Member] | On or After January 1, 2025
Temporary Equity [Line Items]
Multiple of invested capital as minimum return			1.20
Private Placement [Member] | Redeemable Preferred Stock [Member]
Temporary Equity [Line Items]
Shares issued	300,000
Preferred stock dividend rate	12.00%
Preferred stock par value	$ 1.00
Proceeds from issuance of warrants, net of discount			$ 289.5
Payment of directly related issuance costs			18.0
Fair value of warrants		$ 43.0	$ 43.0			$ 43.0
Private Placement [Member] | Series A Warrants [Member]
Temporary Equity [Line Items]
Warrants to purchase common shares	6,800,000
Initial excise price per share	$ 0.01
Proceeds from issuance of warrants, net of discount	$ 289.5
Payment of directly related issuance costs	$ 18.0

[1] ^{The effects of stock-based awards, warrants and redeemable preferred stock were not included in the calculation of diluted earnings per share for the three and six months ended June 30, 2019 due to the net loss for the periods.}