The New Jersey Supreme Court on Monday ordered Horizon Blue Cross Blue Shield, the state's largest health insurer, to turn over a McKinsey & Co. report and other documents it used to establish two tiers of health systems for an insurance plan introduced in 2015.

Providers in the second tier, including Capital Health System Inc. and St. Peter's University Hospital Inc., sued, alleging that Horizon treated them unfairly and breached their contracts when it set up the tiers for its Omnia insurance plan. At the seven Tier One health systems in the Omnia Health Alliance consumers have lower out-of-pocket costs.

The decision overturned an Appellate Court decision that Horizon did not have to provide the documents for discovery in court.

"We continue to agree with the Appellate Court's characterization of plaintiffs' cases and look forward to prevailing on the merits of the case," Horizon spokesman Kevin McArdle said.

In its 2016 annual report, Horizon said that Omnia plans, which cost on average 15 percent less than comparable broad-network plans, had nearly 290,000 members.