Acquisition - Schedule of Unaudited Pro Forma Information (Detail) - Headway - USD ($)	3 Months Ended	9 Months Ended
Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Pro Forma:
Total revenue	$ 334,555	$ 73,324	$ 472,132	$ 207,319
Net income (loss)	$ 157,208	$ 5,508	$ 163,761	$ 12,135
Basic and diluted earnings per share:
Net income per share, basic	$ 1.74	$ 0.06	$ 1.81	$ 0.14
Net income per share, diluted	$ 1.71	$ 0.06	$ 1.78	$ 0.13
Weighted average common shares outstanding, basic	90,517,492	89,590,135	90,370,679	89,208,732
Weighted average common shares outstanding, diluted	92,161,108	91,489,975	91,985,946	91,188,958

Pro forma basic earnings per share or earnings per unit, which is commonly presented in initial public offerings based on the terms of the offering.

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