Income Taxes - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jan. 01, 2018	Jan. 01, 2017	Dec. 31, 2014
Income Tax [Line Items]
Deferred tax asset, federal net operating loss carryforwards	$ 3.0	$ 1.1	$ 3.0
Deferred tax asset, state net operating loss carryforwards	6.8	8.3	6.8
Deferred tax asset, foreign net operating loss carryforwards	9.2	9.1	9.2
Deferred tax asset, U.S. research tax credit carryforwards	1.1	1.1	1.1
Deferred tax asset, U.S. foreign tax credits carryforwards	1.5	3.0	1.5
Deferred tax asset, U.S. alternative minimum tax credits carryforwards	1.0		1.0
Valuation allowance	7.7	10.6	7.7
Total deferred tax assets	86.2	64.2	86.2
Income taxes paid		13.9	13.3	$ 9.6
Statutory tax rate					21.00%	35.00%
Unrecognized tax benefits	1.8	1.9	1.8	2.2			$ 2.0
Accrual for interest and penalties	0.6	0.6	0.6
Unrecognized tax benefits, income tax penalties and interest accrued	2.1	2.2	2.1
Decrease in valuation allowance	$ 2.2
Income tax expense		$ 0.5	$ 17.4	$ 34.1
Effective income tax rate		0.80%	30.60%	34.10%
Benefit associated with tax planning strategy				$ (4.2)
Adjustment of deferred tax assets				2.4
Change in enacted tax rate				$ 0.4
Tax Act transition tax, rate applied to cash		15.50%
Tax Act transition tax, rate applied to earnings in excess of cash		8.00%
Research Tax Credit Carryforward
Income Tax [Line Items]
Deferred tax asset, tax credit carryforwards expiration year		2019
Canada
Income Tax [Line Items]
Decrease in valuation allowance			$ 3.5
Internal Revenue Service (IRS)
Income Tax [Line Items]
Deferred tax asset, net operating loss carryforwards expiration year		2027
Internal Revenue Service (IRS) | Foreign Tax Credit Carryforward
Income Tax [Line Items]
Valuation allowance		$ 3.0
State and Local Jurisdiction
Income Tax [Line Items]
Deferred tax asset, net operating loss carryforwards expiration year		2018
Valuation allowance		$ 1.0
Decrease in valuation allowance		$ (0.8)
Foreign Tax Authority
Income Tax [Line Items]
Deferred tax asset, net operating loss carryforwards expiration year		2025
Deferred tax asset, tax credit carryforwards expiration year		2023
Valuation allowance		$ 1.3
United Kingdom
Income Tax [Line Items]
Valuation allowance		6.3
Decrease in valuation allowance			1.3
Current Deferred Tax Assets [Member]
Income Tax [Line Items]
Unrecognized tax benefits, period increase (decrease)		(0.3)	$ (0.3)
Tax law change | Internal Revenue Service (IRS)
Income Tax [Line Items]
Change in enacted tax rate		23.0
Tax law change | State and Local Jurisdiction
Income Tax [Line Items]
Income tax expense		$ 0.6