Notes Payable - Additional Information (Detail) - USD ($) $ in Thousands		9 Months Ended		12 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Debt Instrument [Line Items]
Total outstanding amounts of notes	[1]			$ 18,774
Principal payments		$ 18,774	$ 2,185
Cash interest paid on Notes		1,991	2,008
13% Senior First Lien Notes [Member]
Debt Instrument [Line Items]
Issued aggregate principal amount		$ 110,000
Notes maturity date		Mar. 19, 2030
13% Senior Second Lien Notes [Member]
Debt Instrument [Line Items]
Issued aggregate principal amount		$ 20,000
Notes maturity date		Mar. 19, 2030
Total outstanding amounts of notes		$ 0		18,800
Principal payments		18,800		$ 2,900
Cash interest paid on Notes		$ 2,000	$ 2,000

[1] Balances derived from audited financial statements as of December 31, 2016.