Income Taxes - Summary of Components of Deferred and Other Tax Assets and Liabilities (Parenthetical) (Detail) $ in Thousands	6 Months Ended
	Jun. 30, 2018 USD ($)
Income Tax Disclosure [Abstract]
Net operating loss carryforwards	$ 11,148
Net operating loss carryforwards expiration period	Expire at various dates between December 31, 2026 and December 31, 2035.