Additional information: condensed financial statements of the Company - Schedule of Condensed Statements of Operations (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Condensed Income Statements, Captions [Line Items]
Revenues	$ 179,529us-gaap_SalesRevenueNet	$ 174,594us-gaap_SalesRevenueNet	$ 140,521us-gaap_SalesRevenueNet
Cost of revenues	(98,459)us-gaap_CostOfRevenue	(93,260)us-gaap_CostOfRevenue	(84,012)us-gaap_CostOfRevenue
Gross profit	81,070us-gaap_GrossProfit	81,334us-gaap_GrossProfit	56,509us-gaap_GrossProfit
Operating expenses
Research and development expenses	(35,287)us-gaap_ResearchAndDevelopmentExpense	(28,832)us-gaap_ResearchAndDevelopmentExpense	(20,357)us-gaap_ResearchAndDevelopmentExpense
Sales and marketing expenses	(29,253)us-gaap_SellingAndMarketingExpense	(26,610)us-gaap_SellingAndMarketingExpense	(20,219)us-gaap_SellingAndMarketingExpense
General and administrative expenses	(29,960)us-gaap_GeneralAndAdministrativeExpense	(23,073)us-gaap_GeneralAndAdministrativeExpense	(18,474)us-gaap_GeneralAndAdministrativeExpense
Total operating expenses	(94,500)us-gaap_OperatingExpenses	(78,515)us-gaap_OperatingExpenses	(59,050)us-gaap_OperatingExpenses
Operating income / (loss)	(11,874)us-gaap_OperatingIncomeLoss	3,839us-gaap_OperatingIncomeLoss	2,125us-gaap_OperatingIncomeLoss
Interest income	6,733us-gaap_InterestIncomeOther	1,189us-gaap_InterestIncomeOther	1,377us-gaap_InterestIncomeOther
Interest expense	(163)us-gaap_InterestExpenseDebt		(1,400)us-gaap_InterestExpenseDebt
Other (loss) / income, net	13,966us-gaap_OtherNonoperatingIncomeExpense	4,679us-gaap_OtherNonoperatingIncomeExpense	564us-gaap_OtherNonoperatingIncomeExpense
Income before income tax	8,403	9,732	2,621
Income tax	1,459us-gaap_IncomeTaxExpenseBenefit	647us-gaap_IncomeTaxExpenseBenefit	(2,239)us-gaap_IncomeTaxExpenseBenefit
Net income	9,862us-gaap_ProfitLoss	10,379us-gaap_ProfitLoss	382us-gaap_ProfitLoss
Net income attributable to the non-controlling interest	(950)	(283)	(121)
Net (loss) / income attributable to Xunlei Limited's common shareholders	(105,366)	2,268	(313)
Xunlei Limited [Member]
Condensed Income Statements, Captions [Line Items]
Revenues	0	0	0
Cost of revenues	(1,673)	(2,264)	(3,075)
Gross profit	(1,673)	(2,264)	(3,075)
Operating expenses
Research and development expenses			(1,369)
Sales and marketing expenses		(241)	(489)
General and administrative expenses	(996)	(972)	(1,315)
Total operating expenses	(996)	(1,213)	(3,173)
Operating income / (loss)	(2,669)	(3,477)	(6,248)
Interest income	6,171	706	1,089
Interest expense	(163)
Other (loss) / income, net	7,602	1,651	(885)
Income from subsidiaries and consolidated VIEs	(129)	11,782	6,547
Income before income tax	10,812	10,662	503
Income tax	0	0	0
Net income	10,812	10,662	503
Net income attributable to the non-controlling interest	0	0	0
Net (loss) / income attributable to Xunlei Limited's common shareholders	$ 10,812	$ 10,662	$ 503

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