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Earnings per Share of Common Stock - Basic and Diluted Loss Per Share of Common Stock Narrative (Detail) - shares | 12 Months Ended
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Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Senior Common Stock |  |  |
Summary Of Computation Of Basic And Diluted Earnings Per Share [Line Items] |  |  |
Anti-dilutive convertible shares of senior common stock excluded from calculation of diluted earnings per share (in shares) | 724,336 | 753,881 | 800,116

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- Definition Summary Of Computation Of Basic And Diluted Earnings Per Share [Line Items] + References No definition available. + Details
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- Definition Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257 + Details
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