Summary of Revenue by Segment and Business Line (Detail) (USD $)
In Thousands, unless otherwise specified

3 Months Ended

12 Months Ended

Dec. 31, 2012

Sep. 30, 2012

Jun. 30, 2012

Mar. 31, 2012

Dec. 31, 2011

Sep. 30, 2011

Jun. 30, 2011

Mar. 31, 2011

Dec. 31, 2012

Dec. 31, 2011

Dec. 31, 2010

Segment Reporting Information [Line Items]

Revenue

$ 801,023

$ 804,888

$ 778,312

$ 739,885

$ 762,775

$ 752,179

$ 751,201

$ 485,379

$ 3,124,108

$ 2,751,534

$ 1,833,737

Intermodal

Segment Reporting Information [Line Items]

Revenue

2,042,286

1,795,289

1,285,163

Truck Brokerage

Segment Reporting Information [Line Items]

Revenue

651,116

576,829

335,000

Logistics

Segment Reporting Information [Line Items]

Revenue

430,706

379,416

213,574

Hub

Segment Reporting Information [Line Items]

Revenue

2,392,289

2,183,914

1,833,737

Hub | Intermodal

Segment Reporting Information [Line Items]

Revenue

1,731,487

1,553,594

1,285,163

Hub | Truck Brokerage

Segment Reporting Information [Line Items]

Revenue

335,213

339,444

335,000

Hub | Logistics

Segment Reporting Information [Line Items]

Revenue

325,589

290,876

213,574

Mode

Segment Reporting Information [Line Items]

Revenue

779,928

586,251

Mode | Intermodal

Segment Reporting Information [Line Items]

Revenue

354,662

258,087

Mode | Truck Brokerage

Segment Reporting Information [Line Items]

Revenue

318,848

238,418

Mode | Logistics

Segment Reporting Information [Line Items]

Revenue

106,418

89,746

Intersegment Elims

Segment Reporting Information [Line Items]

Revenue

(48,109)

(18,631)

Intersegment Elims | Intermodal

Segment Reporting Information [Line Items]

Revenue

(43,863)

(16,392)

Intersegment Elims | Truck Brokerage

Segment Reporting Information [Line Items]

Revenue

(2,945)

(1,033)

Intersegment Elims | Logistics

Segment Reporting Information [Line Items]

Revenue

$ (1,301)

$ (1,206)