Defined Benefit Pension and Other Postretirement Plans - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Employer contributions	$ 0
Pension settlement expenses	1	$ 1
Other Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Benefits paid	2
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Benefits paid	7
Pension settlement expenses	$ 0	$ 0