Earnings per Share - Common Stock Equivalents Not Included in Computation of Diluted Earnings Per Share (Detail) - $ / shares	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Restricted Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	95,054	66,332
Restricted Stock Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	24,782	0
Minimum [Member] | Restricted Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Net Income, Per Outstanding Unit, Amount	$ 12.99	$ 8.84
Minimum [Member] | Restricted Stock Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Net Income, Per Outstanding Unit, Amount	16.62	0
Maximum [Member] | Restricted Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Net Income, Per Outstanding Unit, Amount	15.44	14.49
Maximum [Member] | Restricted Stock Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Net Income, Per Outstanding Unit, Amount	$ 16.62	$ 0