Retirement and Benefit Plans (Defined Benefit Retirement Plans with Overfunded and Underfunded Status) (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Change In Fair Value Roll Forward
Fair value of plan assets at January 1	[1]	$ 166
Fair value of plan assets at December 31	[1]	172	$ 166
Defined Benefit Plan, Change in Benefit Obligation
Interest cost		9	9	$ 10
Underfunded defined benefit pension plans
Defined Benefit Plan Change In Fair Value Roll Forward
Fair value of plan assets at January 1		166	195
Actual return on assets		11	(6)
Contributions		20	4
Settlement		(15)	(17)
Benefits paid		(10)	(10)
Fair value of plan assets at December 31		172	166	195
Defined Benefit Plan, Change in Benefit Obligation
Projected benefit obligation at January 1		220	247
Interest cost		9	9
Settlement		(15)	(17)
Actuarial (gain) loss		2	(9)
Benefits paid		(10)	(10)
Projected benefit obligation at December 31		206	220	$ 247
Underfunded projected benefit obligation at December 31		(34)	(54)
Accumulated benefit obligation at December 31	[2]	$ 206	$ 220

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

[2] (a) Since the Plan’s benefits are 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, 2016 and 2015 .