Property and Equipment, Net - Additional Information (Detail)	3 Months Ended	9 Months Ended
Sep. 30, 2018 USD ($) Building	Sep. 30, 2017 USD ($)	Sep. 30, 2018 USD ($) a ft² Building	Sep. 30, 2017 USD ($)
Property Plant And Equipment Useful Life And Values [Abstract]
Depreciation and amortization expense \| $	$ 1,000,000	$ 394,000	$ 1,700,000	$ 1,200,000
Number of acres of land purchased \| a			15
Number of buildings \| Building	5		5
Gross area of acquired property \| ft²			229,000

The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

Name:	us-gaap_Depreciation
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration