Income Taxes - Components of Deferred Taxes (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Deferred Tax Assets:
Accrued third party obligations, deductible for taxes upon economic performance	$ 17,769	$ 16,973
Provision for doubtful accounts receivable	957	756
Excess of financial statement over tax depreciation	10,905	9,852
Deductible stock compensation expense, net	15,122	11,621
Foreign currency translation adjustment	20,719	3,432
Retained liability for cargo claims	1,555	802
Total gross deferred tax assets	67,027us-gaap_DeferredTaxAssetsGross	43,436us-gaap_DeferredTaxAssetsGross
Deferred Tax Liabilities:
Unremitted foreign earnings, net of related foreign tax credits	(82,262)	(83,186)
Other	0us-gaap_DeferredTaxLiabilitiesOther	(135)us-gaap_DeferredTaxLiabilitiesOther
Total gross deferred tax liabilities	(82,262)us-gaap_DeferredIncomeTaxLiabilities	(83,321)us-gaap_DeferredIncomeTaxLiabilities
Net deferred tax liabilities	(15,235)us-gaap_DeferredTaxLiabilities	(39,885)us-gaap_DeferredTaxLiabilities
Current deferred tax assets	(20,279)us-gaap_DeferredTaxAssetsNetCurrent	(18,396)us-gaap_DeferredTaxAssetsNetCurrent
Noncurrent deferred tax liabilities	$ (35,514)	$ (58,281)

Amount of deferred tax liability attributable to taxable temporary differences.

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