Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating Loss Carryforwards [Line Items]
Valuation allowance for net deferred tax assets	$ 6.4	$ 7.2
Reduction in valuation allowance	0.8
Valuation allowance result in benefit of provision of income tax	(22.5)
Income tax expense (benefit)	7.2	(17.2)
Income from continuing operations before income taxes	20.5	12.2	$ 5.8
Income tax expense from discontinued operations	1.8	(1.9)	$ 0.0
Income from discontinued operation before tax	4.8
Gross deferred tax assets	25.9	34.8
Deferred tax assets, net of valuation allowance	19.5	27.6
Deferred tax liabilities	9.2	8.5
Net deferred tax assets	10.3	$ 19.1
Domestic Country [Member]
Operating Loss Carryforwards [Line Items]
Federal tax loss carryforwards	$ 30.0
Operating loss carryforwards expiration year	2030
State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards expiration year	2035