Significant Accounting Policies - Additional Information (Detail)	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2017 USD ($)	Sep. 30, 2017 USD ($)	Dec. 31, 2017 USD ($) a Project	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Significant Accounting Policies [Line Items]
Severance costs			$ 287,000	$ 6,426,000
Impairment of long-lived assets					$ 36,177,000
Allowance for doubtful accounts			1,602,000	2,804,000
Other receivables			546,000	650,000
Restricted cash			10,216,000	0
Lower of cost or market inventory adjustment			0	1,515,000	4,546,000
Production cost			40,664,000	47,318,000	33,724,000
Start-up costs			0	15,000	797,000
Research and development expenses			$ 4,417,000	$ 3,817,000	$ 7,047,000
Maximum
Significant Accounting Policies [Line Items]
Receivables collection period			30 days
Maturity period for all highly liquid investments when purchased to be cash equivalents			3 months
Capitalized software estimated useful life			5 years
Georgia and Alabama
Significant Accounting Policies [Line Items]
Number of projects suspended | Project			2
Percentage of value of assets of two projects on construction in progress			85.00%
Projects completed percentage			90.00%
Area of land and leasehold interests | a			4,618
Millen Georgia
Significant Accounting Policies [Line Items]
Impairment of long-lived assets	$ 125,759,000	$ 125,759,000
Millen Georgia | Construction in Progress
Significant Accounting Policies [Line Items]
Impairment of long-lived assets	$ 50,170,000
Marshfield, Wisconsin
Significant Accounting Policies [Line Items]
Area of land and leasehold interests | a			113