Other Liabilities - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Additional Other Liabilities Disclosure [Abstract]
Restructuring expenses	$ 5	$ 12	$ 8	$ 24	[1]

[1] 2017 figures have been recast following the retrospective adoption on January 1, 2018, of the updated accounting standards for revenue recognition (ASC 606) and retirement benefits accounting (ASU 2017-07).