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Basis of Presentation and Significant Accounting Policies - Additional Information (Detail) (USD $)
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1 Months Ended | 3 Months Ended | 6 Months Ended | 1 Months Ended | 3 Months Ended | 1 Months Ended | 3 Months Ended | 1 Months Ended | 3 Months Ended | 6 Months Ended | 12 Months Ended | 6 Months Ended | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
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Sep. 26, 2012
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Jun. 30, 2013
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Jun. 30, 2012
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Jun. 30, 2013
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Jun. 30, 2012
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Dec. 31, 2012
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Oct. 17, 2012
Debt Portion of Convertible Note [Member]
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Sep. 26, 2012
Debt Portion of Convertible Note [Member]
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Jun. 30, 2013
Debt Portion of Convertible Note [Member]
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Oct. 17, 2012
Equity Portion of Convertible Note [Member]
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Sep. 26, 2012
Equity Portion of Convertible Note [Member]
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Jun. 30, 2013
Equity Portion of Convertible Note [Member]
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Sep. 26, 2012
Convertible Debt [Member]
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Jun. 30, 2013
Convertible Debt [Member]
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Jun. 30, 2013
Portion of Debt Issuance Allocated to Long-Term Debt [Member]
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Sep. 26, 2012
Portion of Debt Issuance Allocated to Long-Term Debt [Member]
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Jun. 30, 2013
Computer Software, Intangible Asset [Member]
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Dec. 31, 2012
Computer Software, Intangible Asset [Member]
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Jun. 30, 2013
Portion of Debt Issuance Allocated to Equity [Member]
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Sep. 26, 2012
Portion of Debt Issuance Allocated to Equity [Member]
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Jun. 30, 2013
Minimum [Member]
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Jun. 30, 2013
Maximum [Member]
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| Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items] | ||||||||||||||||||||||
| Typical Percentage Of Credit Losses Reimbursed To Freight Forwarding By Independently Owned Stations | 70-80% | |||||||||||||||||||||
| Percentage Of Credit Losses Reimbursed To Freight Forwarding By Independently Owned Stations | 70.00% | 80.00% | ||||||||||||||||||||
| Taxes and Duties Collected on Behalf of Customer | $ 1,500,000 | $ 700,000 | $ 2,300,000 | $ 1,400,000 | ||||||||||||||||||
| Finite-Lived Intangible Asset, Useful Life | 3 years | 3 years | 3 months | 12 years | ||||||||||||||||||
| Convertible senior notes outstanding | 143,800,000 | |||||||||||||||||||||
| Debt Instrument, Interest Rate, Stated Percentage | 4.50% | 4.50% | ||||||||||||||||||||
| Debt Instrument, due date | Oct. 01, 2017 | Oct. 01, 2017 | ||||||||||||||||||||
| Convertible Debt | 106,800,000 | 92,800,000 | ||||||||||||||||||||
| Debt Instrument, Convertible, Carrying Amount of Equity Component | 31,700,000 | 27,500,000 | ||||||||||||||||||||
| Debt Issuance Cost | 500,000 | 3,600,000 | 4,100,000 | 100,000 | 1,100,000 | 1,200,000 | ||||||||||||||||
| Convertible Debt, Conversion Rate, Shares Per $1000 In Principal Amount | 60.8467 | 60.8467 | ||||||||||||||||||||
| Convertible Debt, Conversion Rate, Principal Amount Increment | 1,000 | 1,000 | ||||||||||||||||||||
| Debt Instrument, Convertible, Conversion Price (in Dollars per share) | $ 16.43 | $ 16.43 | $ 16.43 | |||||||||||||||||||
| Convertible Debt, Fair Value Disclosures | 177,400,000 | 177,400,000 | ||||||||||||||||||||
| Debt Instrument, Convertible, Beneficial Conversion Feature | 0 | |||||||||||||||||||||
| Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate | 0.00% | |||||||||||||||||||||
| Capitalized Computer Software, Gross | $ 1,600,000 | $ 1,600,000 | $ 1,200,000 | |||||||||||||||||||