Retirement and Benefit Plans (Plan Assets Measured at Fair Value on a Recurring Basis) (Detail) - USD ($) $ in Millions		Dec. 31, 2019		Dec. 31, 2018
Defined Benefit Plan Disclosure
Plan assets	[1]	$ 175		$ 164
Cash equivalents
Defined Benefit Plan Disclosure
Plan assets	[1]	14		25
Mutual and exchange-traded funds
Defined Benefit Plan Disclosure
Plan assets	[1]	76		46
Debt securities
Defined Benefit Plan Disclosure
Plan assets	[1]	85		65
Debt securities | U.S. Treasury and federal agencies securities
Defined Benefit Plan Disclosure
Plan assets	[1]	63		46
Debt securities | Non-agency mortgage-backed securities | Commercial mortgage-backed securities
Defined Benefit Plan Disclosure
Plan assets	[1]	1		1
Debt securities | Asset-backed securities and other debt securities
Defined Benefit Plan Disclosure
Plan assets	[2]	21	[1]	18
Collective funds
Defined Benefit Plan Disclosure
Plan assets	[1],[3]			28
Excluding collective funds
Defined Benefit Plan Disclosure
Plan assets	[1]			136
Fair Value, Inputs, Level 1
Defined Benefit Plan Disclosure
Plan assets	[1]	147
Fair Value, Inputs, Level 1 | Cash equivalents
Defined Benefit Plan Disclosure
Plan assets		14	[1]	25	[4]
Fair Value, Inputs, Level 1 | Mutual and exchange-traded funds
Defined Benefit Plan Disclosure
Plan assets		76	[1]	46	[4]
Fair Value, Inputs, Level 1 | Debt securities
Defined Benefit Plan Disclosure
Plan assets		57	[1]	43	[4]
Fair Value, Inputs, Level 1 | Debt securities | U.S. Treasury and federal agencies securities
Defined Benefit Plan Disclosure
Plan assets		57	[1]	43	[4]
Fair Value, Inputs, Level 1 | Debt securities | Non-agency mortgage-backed securities | Commercial mortgage-backed securities
Defined Benefit Plan Disclosure
Plan assets		0	[1]	0	[4]
Fair Value, Inputs, Level 1 | Debt securities | Asset-backed securities and other debt securities
Defined Benefit Plan Disclosure
Plan assets	[2]	0	[1]	0
Fair Value, Inputs, Level 1 | Excluding collective funds
Defined Benefit Plan Disclosure
Plan assets	[4]			114
Fair Value, Inputs, Level 2
Defined Benefit Plan Disclosure
Plan assets	[1]	28
Fair Value, Inputs, Level 2 | Cash equivalents
Defined Benefit Plan Disclosure
Plan assets		0	[1]	0	[4]
Fair Value, Inputs, Level 2 | Mutual and exchange-traded funds
Defined Benefit Plan Disclosure
Plan assets		0	[1]	0	[4]
Fair Value, Inputs, Level 2 | Debt securities
Defined Benefit Plan Disclosure
Plan assets		28	[1]	22	[4]
Fair Value, Inputs, Level 2 | Debt securities | U.S. Treasury and federal agencies securities
Defined Benefit Plan Disclosure
Plan assets		6	[1]	3	[4]
Fair Value, Inputs, Level 2 | Debt securities | Non-agency mortgage-backed securities | Commercial mortgage-backed securities
Defined Benefit Plan Disclosure
Plan assets		1	[1]	1	[4]
Fair Value, Inputs, Level 2 | Debt securities | Asset-backed securities and other debt securities
Defined Benefit Plan Disclosure
Plan assets	[2]	21	[1]	18
Fair Value, Inputs, Level 2 | Excluding collective funds
Defined Benefit Plan Disclosure
Plan assets	[4]			22
Fair Value, Inputs, Level 3
Defined Benefit Plan Disclosure
Plan assets	[1]	0
Fair Value, Inputs, Level 3 | Cash equivalents
Defined Benefit Plan Disclosure
Plan assets	[1]	0		0
Fair Value, Inputs, Level 3 | Mutual and exchange-traded funds
Defined Benefit Plan Disclosure
Plan assets	[1]	0		0
Fair Value, Inputs, Level 3 | Debt securities
Defined Benefit Plan Disclosure
Plan assets	[1]	0		0
Fair Value, Inputs, Level 3 | Debt securities | U.S. Treasury and federal agencies securities
Defined Benefit Plan Disclosure
Plan assets	[1]	0		0
Fair Value, Inputs, Level 3 | Debt securities | Non-agency mortgage-backed securities | Commercial mortgage-backed securities
Defined Benefit Plan Disclosure
Plan assets	[1]	0		0
Fair Value, Inputs, Level 3 | Debt securities | Asset-backed securities and other debt securities
Defined Benefit Plan Disclosure
Plan assets	[2]	$ 0	[1]	0
Fair Value, Inputs, Level 3 | Excluding collective funds
Defined Benefit Plan Disclosure
Plan assets	[1]			$ 0

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

[2] Includes corporate bonds.

[3] Certain investments that are measured at fair value using the NAV per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the fair value of Plan assets presented elsewhere within this footnote.

[4] During the year ended December 31, 2018, no assets or liabilities were transferred between Level 1 and Level 2.