The health insurer Humana will stop providing employer-sponsored commercial coverage as it focuses on bigger parts of its business, like Medicare Advantage.

The insurer said Thursday it will leave the business over the next 18 to 24 months. It includes medical coverage provided through private companies and for federal government employees.

Human will still provide insurance through its military service business. It covers active duty service members, their families and retirees and totals nearly 6 million people. It also will still provide employer-sponsored specialty coverage like vision and dental benefits.

Employer-sponsored health insurance is one of the more common ways for Americans to get coverage. But at nearly a million people, it amounts to a small part of Humana's enrollment of more than 13 million.

Humana's business largely centers on the military and Medicare Advantage plans. Those are privately run versions of the federal government's Medicare program for people age 65 and older.

Humana also runs Medicaid coverage in several states.

CEO Bruce Broussard said in a prepared statement that the exit from employer-sponsored coverage lets Humana focus on its "greatest opportunities for growth."

The company also said its employer-sponsored business "was no longer positioned to sustainably meet the needs of commercial members over the long term or support the company's long-term strategic plans."

Employer-sponsored enrollment growth has largely slowed for insurers, including market leaders like UnitedHealthcare. Companies have turned more to government-backed coverage like Medicare Advantage or Medicaid for growth.

They also have pushed deeper into managing prescription drug plans and providing care in order to control health care costs.

Humana does not expect the change to affect adjusted profit this year, which the company projects to be at least $28 per share.

Analysts forecast $28.06 per share, according to FactSet.

Shares of Humana Inc., based in Louisville, Kentucky, climbed more than $4 to $507.91 Thursday.