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Employee Benefit Plans - Individually Significant Information (Detail) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Multiemployer Plans [Line Items]
High end of funded percentage of multiemployer plans in critical status		65.00%
High end of funded percentage of multiemployer plans in endangered status		80.00%
Surcharge percentage during first twelve months on contribution rates for plans certified as endangered, seriously endangered or critical		5.00%
Period for which surcharge is 5% on contribution rates for plans certified as endangered, seriously endangered or critical		12 months
Accrued benefit liabilities		$ 21	$ 29
Surcharge percentage after first twelve months on contribution rates for plans certified as endangered, seriously endangered or critical		10.00%
Company Contributions		$ 47	$ 47	$ 47
Minimum [Member]
Multiemployer Plans [Line Items]
Projected insolvency period		15 years
Maximum [Member]
Multiemployer Plans [Line Items]
Projected insolvency period		20 years
Suburban Teamsters of Northern Illinois Pension Plan [Member]
Multiemployer Plans [Line Items]
Minimum percentage of total contributions provided by the Company relating to multiemployer plans			5.00%	5.00%
Company Contributions		$ 3	$ 3	$ 3
Western Pennsylvania Teamsters and Employers Pension Plan [Member]
Multiemployer Plans [Line Items]
Company Contributions			1	1
Multiemployer Health and Welfare Plan [Member]
Multiemployer Plans [Line Items]
Company Contributions		43	42	$ 40
Withdrawal from Multiemployer Pension Plans [Member]
Multiemployer Plans [Line Items]
Charge to "Operating" expenses	$ 11	3	12
Withdrawal from Multiemployer Pension Plans [Member] | Western Pennsylvania Teamsters and Employers Pension Plan [Member]
Multiemployer Plans [Line Items]
Charge to "Operating" expenses		$ 2	$ 11

X

- Definition

Amount of contributions made to multiemployer plan by employer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 80
-Section 50
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=65877416&loc=SL14450702-114947

Reference 2: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 715
-SubTopic 80
-Section 50
-Paragraph 9
-URI http://asc.fasb.org/extlink&oid=65877416&loc=SL14450691-114947

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Amount of liability, recognized in statement of financial position, for defined benefit pension and other postretirement plans.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64852052&loc=d3e1703-114919

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
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-Section S99
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-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 3: http://www.xbrl.org/2003/role/presentationRef
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-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

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Minimum percentage of total contributions provided by the company relating to multi employer plans.

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Period for which surcharge is five percent on contribution rates for plans certified as endangered seriously endangered or critical.

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