Annual report pursuant to Section 13 and 15(d)

Acquisitions and Recent Transactions - 2017 Equity Transactions - Additional Information (Detail)

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Acquisitions and Recent Transactions - 2017 Equity Transactions - Additional Information (Detail) - shares
12 Months Ended
Aug. 09, 2017
Feb. 24, 2017
Dec. 31, 2018
Dec. 31, 2017
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]        
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period       211,658
Restricted Stock [Member]        
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]        
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period     0  
Restricted Stock [Member] | Executive Officer [Member]        
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]        
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period 33,066      
Restricted Stock [Member] | Management [Member]        
Summary of Investments, Other than Investments in Related Parties, Reportable Data [Line Items]        
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period   178,592