Other Liabilities - Summary of Other Liabilities (Parenthetical) (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018
Other Liabilities Disclosure [Line Items]
Amortization period of Legacy facilities credit as reduction to cost of sales		40 years
Legacy Facilities Credit [Member]
Other Liabilities Disclosure [Line Items]
Amount of compensation paid	$ 44.3
CCR [Member] | Legacy Facilities Credit [Member]
Other Liabilities Disclosure [Line Items]
Amortization period of Legacy facilities credit as reduction to cost of sales		40 years