Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended			12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2017
Income Taxes [Line Items]
Unrecognized tax benefits, interest expense	$ 0
Effective income tax rate from continuing operations	5.10%		46.10%
Provision for income taxes	$ 1,650,000		$ 5,887,000
Income tax provision (benefit), federal rate	21.00%			35.00%
Estimated income tax benefit		$ 67,000,000
Net income tax provision		34,000,000
Income tax benefit valuation allowance		$ 101,000,000
Undistributed earnings and profits in foreign subsidiary	$ 0
Maximum
Income Taxes [Line Items]
Unrecognized tax benefits, interest expense			$ 100,000