The December issue of Details magazine will be its last, making the men’s fashion title the latest casualty of the declining print advertising market.

Bob Sauerberg, president of Condé Nast, which owns Details, announced the closure to staff on Wednesday.

It’s expected that GQ, Condé Nast’s other men’s fashion magazine, will increase the frequency of its twice-a-year GQ Style publication in a bid to retain the fashion designers that currently advertise in Details.

The restructuring at Condé Nast comes as many publishers are grappling with declining revenue as marketers continue to pull ad dollars from traditional media such as print to fund their push into digital advertising. Although magazine publishers are showing increased digital ad revenues, those gains have typically not been enough to make up for the losses on the print side.

“It’s been tough the last few months,” Mr. Sauerberg said in an interview. Condé Nast is a unit of closely held Advance Publications Inc. “Consumers love the magazine. It’s not fair or right.” He noted that the publication’s circulation has grown in print and digitally. Mr. Sauerberg will become Condé Nast’s chief executive in January.

Mr. Sauerberg estimated that at least 20% of the 60 staffers who work at Details will find other jobs inside Condé Nast, although an internal memo to staffers said that the title’s editor in chief Dan Peres and publisher and chief revenue officer Drew Schutte are leaving the company.

The October issue of men’s fashion title Details. The Condé Nast-owned magazine will cease publication with its December edition. Photo: Samantha Nandez/BFA

In a related move, Condé Nast is combining the advertising sales staffs of Self and Glamour magazines, enabling Condé Nast to pitch the combined audiences of both publications to potential advertisers. The magazines each cover women’s health, wellness and career, with Glamour also focusing on beauty and fashion.

Self will continue as a print magazine. Mary Murcko, Self’s publisher and chief revenue officer, is leaving the company as a result of the consolidation, according to the memo.

“This move gives us the scale to go to market that our ad partners want,” said Mr. Sauerberg. He noted that Condé Nast has seen significant revenue gains since combining its Bon Appétit food magazine with its Epicurious.com food website in August 2014.

Condé Nast is aggressively cutting expenses as it seeks to increase its bets on flagship publications that include Vanity Fair, GQ, the New Yorker, Vogue and Wired. This year, Condé Nast has focused primarily on building its digital offerings for advertisers, most recently acquiring closely held Pitchfork Media Inc., the owner of online music publication Pitchfork.com, in October.

Details, founded in 1982, was acquired by Condé Nast in 1988. The magazine targets men in their late 20s and 30s interested in fashion, culture and men’s grooming, with an editorial approach more irreverent than rivals Esquire or GQ. Stories on Detail’s website include “This Crazy-Looking Hoodie Will Help You Chill Out—for $330” and “What Holiday Bingeing Really Does to Your Body.”

A spokesman for Condé Nast said that details.com will gradually transition to gqstyle.com.

Write to Jeffrey Trachtenberg at jeffrey.trachtenberg@wsj.com