Income Taxes - Additional Information (Detail)	3 Months Ended				12 Months Ended
	Dec. 31, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2018	Dec. 31, 2017 USD ($) Occurrence_Per_Year	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Income Tax Benefit [Line Items]
Income tax provision (benefit)						$ 19,615,000	$ 5,030,000	$ 3,529,000
Non-cash charges associated with impairment of certain state income net operating loss carryforward						3,700,000
Increase in valuation allowance	$ (22,000,000)			$ (3,700,000)		13,526,000	3,700,000	3,000,000
Gross deferred tax assets	22,885,000			28,092,000		22,885,000	28,092,000
Valuation allowance	21,726,000			8,200,000		$ 21,726,000	8,200,000	$ 4,500,000	$ 1,500,000
Increase in deferred tax asset valuation allowance	12,400,000	$ 1,100,000
Pre-tax income							$ 8,900,000
Pretax income period							3 years
U.S. federal corporate tax rate						34.00%	34.00%	34.00%
Number of occurances of transition tax | Occurrence_Per_Year						1
Taxable income associated with one-time transition tax on earnings of certain foreign subsidiaries						$ 266,000
Deferred income tax asset,foreign subsidiary	$ 0					$ 0
Statutory federal tax rate to income from continuing operations	34.00%					34.00%
Cumulative adjustment to retained earnings			$ 1,400,000
Unrecognized tax benefits, penalties and interest accrued	$ 0			$ 0		$ 0	$ 0	$ 0
Tax benefit unrecognized	0					$ 0
Scenario Plan [Member]
Income Tax Benefit [Line Items]
U.S. federal corporate tax rate					21.00%
Maximum [Member]
Income Tax Benefit [Line Items]
U.S. federal corporate tax rate						35.00%
Future Economic Benefit [Member]
Income Tax Benefit [Line Items]
Increase in valuation allowance						$ 10,900,000
Expire In Two Thousand And Thirty Seven [Member]
Income Tax Benefit [Line Items]
Foreign tax credits	1,000,000					1,000,000
Expire In Two Thousand And Thirty Seven [Member] | Federal [Member]
Income Tax Benefit [Line Items]
Net operating loss carryforwards	80,700,000					80,700,000
Expire In Two Thousand And Thirty Seven [Member] | State [Member]
Income Tax Benefit [Line Items]
Net operating loss carryforwards	80,700,000					80,700,000
Expire in 2020 [Member]
Income Tax Benefit [Line Items]
Net operating loss carryforwards	36,500,000					36,500,000
Foreign tax credits	$ 1,000,000					$ 1,000,000
Earliest Tax Year [Member]
Income Tax Benefit [Line Items]
Open tax year subject to examination						2004
Latest Tax Year [Member]
Income Tax Benefit [Line Items]
Open tax year subject to examination						2016