Summary of Net-of-Tax Amounts Recorded in OCI Relating to Pension and OPEB Plans (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Summary of the net-of-tax amounts recorded in OCI relating to pension and OPEB plans
Gain (loss) arising during the year, net of tax expense (benefit) of ($72) in 2016, $44 in 2015 and ($240) in 2014	$ (191)	$ 45	$ (494)
Distribution to Baxalta, net of tax expense of $73		198
Amortization of loss to earnings, net of tax expense of $36 in 2016, $61 in 2015 and $47 in 2014	94	120	94
Pension and other employee benefits (loss) gain	$ (97)	$ 363	$ (400)