Retirement and Benefit Plans (Defined Benefit Retirement Plans with Overfunded and Underfunded Status) (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018		Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Change In Fair Value Roll Forward
Fair value of plan assets at January 1		$ 185
Fair value of plan assets at December 31		164		$ 185
Defined Benefit Plan, Change in Benefit Obligation
Interest cost		7		8	$ 9
Underfunded defined benefit pension plans
Defined Benefit Plan Change In Fair Value Roll Forward
Fair value of plan assets at January 1		185		172
Actual return on assets		0		28
Contributions		3		6
Settlement		0		11
Benefits paid		3		10
Fair value of plan assets at December 31		0		185	172
Defined Benefit Plan, Change in Benefit Obligation
Projected benefit obligation at January 1		209		206
Interest cost		1		8
Settlement		0		11
Actuarial (gain) loss		1		(16)
Benefits paid		3		10
Projected benefit obligation at December 31		18		209	206
Projected benefit obligation at December 31		(18)		(24)
Accumulated benefit obligation at December 31		18	[1]	209
Overfunded defined benefit pension plans
Defined Benefit Plan Change In Fair Value Roll Forward
Fair value of plan assets at January 1		0		0
Actual return on assets		(6)		0
Settlement		9		0
Benefits paid		6		0
Fair value of plan assets at December 31		164		0	0
Defined Benefit Plan, Change in Benefit Obligation
Projected benefit obligation at January 1		0		0
Interest cost		6		0
Settlement		9		0
Actuarial (gain) loss		16		0
Benefits paid		6		0
Projected benefit obligation at December 31		163		0	$ 0
Projected benefit obligation at December 31		1		0
Accumulated benefit obligation at December 31	[2]	$ 163		$ 0

[1] 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, 2018 and 2017 .

[2] 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 December 31, 2018 .