Charges and Credits - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019
Charges And Credits [Line Items]
Charges and credits		$ 0	$ 0
Impairments and Other | Headcount Reductions
Charges And Credits [Line Items]
Charges and credits	$ 164,000,000
Charges and credits, pre tax	$ 184,000,000