Quarterly report pursuant to Section 13 or 15(d)

Loss per Share of Common Stock - Basic and Diluted Loss Per Share of Common Stock Additional Information (Detail)

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Loss per Share of Common Stock - Basic and Diluted Loss Per Share of Common Stock Additional Information (Detail) - shares
3 Months Ended 9 Months Ended
Sep. 30, 2017
Sep. 30, 2016
Sep. 30, 2017
Sep. 30, 2016
Senior Common Stock        
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]        
Anti-dilutive convertible shares of senior common stock excluded from calculation of diluted earnings per share 773,553 800,116 773,553 800,116