Consolidated Statement of Stockholders' Equity (Parenthetical)	Jan. 20, 2017	Dec. 06, 2016
Stockholders equity, stock split		On December 6, 2016, our Board of Directors declared a two-for-one stock split of The Navigators Group, Inc. Common stock, to be effected in the form of a stock dividend.
Stock split ratio		2
Subsequent Event [Member]
Stockholders equity, stock split	We completed a two-for-one stock split on January 20, 2017.
Stock split ratio	2

Description of the stock split arrangement. Also provide the retroactive effect given by a stock split that occurs after the balance date but before the release of financial statements.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Stock Split
-URI http://asc.fasb.org/extlink&oid=6525746

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SAB Topic 4.C)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187143-122770

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