Summary of Reclassifications out of Accumulated Other Comprehensive Loss (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($)
Amortization of defined pension and other postretirement benefit items:
Amortization of net actuarial gains, before income taxes	$ 0.3	[1]
Deferred income tax expense on pension liability adjustments	(0.1)
Gains reclassified into loss, net of income taxes	$ 0.2

[1] This component of accumulated other comprehensive loss is included in the computation of net periodic benefit expense. See Note 14—Employee Benefit Plans for additional details on net periodic benefit expense.