Related-Party Transactions - Additional Information (Detail) - 417 Oakbend, LP [Member] - USD ($) $ in Millions	1 Months Ended			12 Months Ended
	Nov. 30, 2015	Sep. 30, 2015	May 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Related Party Transaction [Line Items]
Payments for rent				$ 0.4	$ 0.4	$ 0.3
Registration and legal fees expenses	$ 1.4	$ 1.4	$ 1.4
Registration rights agreement date				Dec. 30, 2013
Chief Sales Officer [Member]
Related Party Transaction [Line Items]
General partnership ownership interest in related party, percentage				0.01%
Limited partnership interest in related party, percentage				10.49%