Leases - Additional Information (Detail) ft² in Thousands	1 Months Ended
	Jan. 31, 2012 USD ($) ft² Option	Dec. 31, 2017 USD ($) ft²
Leases [Abstract]
Area of office spaces | ft²	66	44
Lease term	120 months
Number of options to extend the term | Option	2
Extend option term	5 years
Option to early terminate, period	5 years
Allowance for tenant improvements	$ 3,900,000
Sublease payments receivable within five months		$ 0