Goodwill and Intangible Assets (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended
Sep. 30, 2013
Rollforward of goodwill by reportable segment
Goodwill balance as of December 31, 2012	$ 442,143
Acquisitions	77,041
Adjustments to goodwill for purchase accounting	(3,322)
Goodwill balance as of September 30, 2013	515,862
LTL [Member]
Rollforward of goodwill by reportable segment
Goodwill balance as of December 31, 2012	197,456
Acquisitions	0
Goodwill balance as of September 30, 2013	197,313
TL [Member]
Rollforward of goodwill by reportable segment
Goodwill balance as of December 31, 2012	202,547
Acquisitions	8,248
Goodwill balance as of September 30, 2013	207,612
TMS [Member]
Rollforward of goodwill by reportable segment
Goodwill balance as of December 31, 2012	42,140
Acquisitions	68,793
Goodwill balance as of September 30, 2013	$ 110,937

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=14024403&loc=d3e13816-109267

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266

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Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

+ References

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Amount of increase (decrease) from adjustments after acquisition date under purchase accounting of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (g)

-URI http://asc.fasb.org/extlink&oid=14024403&loc=d3e13816-109267

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 10

-Section 25

-Paragraph 16

-URI http://asc.fasb.org/extlink&oid=21917927&loc=d3e961-128460

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