Severance and Restructuring Charges - Additional Information (Detail) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2018 USD ($)	Dec. 31, 2015 item
Restructuring Cost And Reserve [Line Items]
Number of restructuring actions commenced | item		2
Restructuring plan, commencement year	2018
Restructuring plan, completion year	2020
Minimum [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring plan, anticipated cost	$ 30
Minimum [Member] | Facility Consolidations [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring plan, anticipated cost	23
Minimum [Member] | Workforce Reductions [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring plan, anticipated cost	7
Maximum [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring plan, anticipated cost	40
Maximum [Member] | Facility Consolidations [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring plan, anticipated cost	28
Maximum [Member] | Workforce Reductions [Member]
Restructuring Cost And Reserve [Line Items]
Restructuring plan, anticipated cost	$ 12