Employer Sponsored Benefit Plan - Narrative (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Future amortization of gain (loss)	$ (1.0)
Discount rate, benefit obligation	3.71%	4.21%
Expected return on plan assets, benefit obligation	5.80%	6.30%
Defined Contribution Plan:
Employer Contributions to 401(k) Plan	$ 2.6	$ 2.5	$ 2.3
Matching contribution, percent of employees' gross pay	5.00%
Matching contribution, percent of employees' gross pay, first 3%	100.00%
Matching contribution, percent of employees' gross pay, remaining 2%	50.00%
Minimum
Defined Benefit Plan Disclosure [Line Items]
Estimated future employer contributions in next fiscal year	$ 3.0
Maximum
Defined Benefit Plan Disclosure [Line Items]
Estimated future employer contributions in next fiscal year	4.0
United States
Defined Benefit Plan Disclosure [Line Items]
Pension plan liability	7.7	13.0
Increase in OCI pension adjustment	2.1	2.4
Foreign Plan
Defined Benefit Plan Disclosure [Line Items]
Pension plan liability	1.9	1.5
Accumulated other comprehensive loss, net of tax	$ 0.4	$ 0.4