Additional information: condensed financial statements of the Company - Schedule of Condensed Balance Sheets (Parenthetical) (Detail) - shares	Dec. 31, 2019	Dec. 31, 2018
Consolidated Balance Sheet Statements Captions [Line Items]
Treasury stock, shares	29,711,964	32,354,429
Xunlei Limited [Member]
Consolidated Balance Sheet Statements Captions [Line Items]
Treasury stock, shares	29,711,964	32,354,429

Number of common and preferred shares that were previously issued and that were repurchased by the issuing entity and held in treasury on the financial statement date. This stock has no voting rights and receives no dividends.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.29,30)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6405813&loc=d3e23239-112655

Name:	us-gaap_TreasuryStockShares
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant