Information Regarding Reportable Business Segments (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 28, 2015	Mar. 29, 2014	Dec. 27, 2014
Segment Reporting Information [Line Items]
External revenue	$ 762,380us-gaap_Revenues	$ 688,197us-gaap_Revenues
Investment income	354us-gaap_InterestIncomeOperating	363us-gaap_InterestIncomeOperating
Internal revenue	6,396us-gaap_RevenueFromRelatedParties	5,792us-gaap_RevenueFromRelatedParties
Operating income	49,045us-gaap_OperatingIncomeLoss	45,014us-gaap_OperatingIncomeLoss
Expenditures on long-lived assets	2,450	732
Goodwill	31,134us-gaap_Goodwill	31,134us-gaap_Goodwill	31,134us-gaap_Goodwill
Transportation Logistics
Segment Reporting Information [Line Items]
External revenue	751,796	678,853
Operating income	43,730	38,984
Expenditures on long-lived assets	2,450	732
Goodwill	31,134	31,134
Insurance
Segment Reporting Information [Line Items]
External revenue	10,584	9,344
Investment income	354	363
Internal revenue	6,396	5,792
Operating income	$ 5,315	$ 6,030

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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Amount of operating interest income, including, but not limited to, amortization and accretion of premiums and discounts on securities.

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The net result for the period of deducting operating expenses from operating revenues.

+ References

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- Definition

The cash outflow associated with the acquisition of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale; includes cash outflows to pay for construction of self-constructed assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Investing Activities

-URI http://asc.fasb.org/extlink&oid=6516133

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 13

-Subparagraph (c)

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Amount of revenue, fees and commissions earned from transactions between (a) a parent company and its subsidiaries; (b) subsidiaries of a common parent; (c) an entity and trusts for the benefit of employees, for example, but not limited to, pension and profit-sharing trusts that are managed by or under the trusteeship of the entity's management; (d) an entity and its principal, owners, management, or members of their immediate families; and (e) affiliates.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.1(e))

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Article 5

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Related Parties

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Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 946

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-Section S99

-Paragraph 1

-Subparagraph (SX 210.6-07.1(c))

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Reference 5: http://www.xbrl.org/2003/role/presentationRef

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-Number 210

-Section 07

-Paragraph b

-Subparagraph 1

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Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

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