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Earnings Per Share and Earnings Per Unit - Additional Information (Detail) - shares
3 Months Ended 9 Months Ended
Sep. 30, 2019
Sep. 30, 2018
Sep. 30, 2019
Sep. 30, 2018
Restricted Stock [Member]        
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]        
Securities not included in the effect of dilutive securities 73,816 88,621 76,565 105,935
Stock Options [Member]        
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]        
Securities not included in the effect of dilutive securities       7,333