Defined Benefit Retirement Plans with Overfunded and Underfunded Status (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Change In Fair Value Roll Forward [Abstract]
Fair value of plan assets at January 1	[1]	$ 195
Fair value of plan assets at December 31	[1]	166	$ 195
Defined Benefit Plan, Change in Benefit Obligation
Interest cost		9	10	$ 10
Underfunded Defined Benefit Pension Plans
Defined Benefit Plan Change In Fair Value Roll Forward [Abstract]
Fair value of plan assets at January 1		195	200
Actual return on plan assets		(6)	12
Contributions		4	3
Settlement		(17)	(11)
Benefits paid		(10)	(9)
Fair value of plan assets at December 31		166	195	200
Defined Benefit Plan, Change in Benefit Obligation
Projected benefit obligation at January 1		247	221
Interest cost		9	10
Settlement		(17)	(11)
Actuarial (gain) loss		(9)	36
Benefits paid		(10)	(9)
Projected benefit obligation at December 31		220	247	$ 221
Underfunded projected benefit obligation at December 31		(54)	(52)
Accumulated benefit obligation at December 31	[2]	$ 220	$ 247

[1] For further information on fair value hierarchy levels, refer to Note 1.

[2] Since the Plan’s benefits were frozen, the rate of compensation increase is no longer an assumption used to calculate the accumulated benefit obligation. Therefore, the accumulated benefit obligation was the same as the projected benefit obligation at both December 31, 2015 and 2014.