Oakland, Calif.-based Kaiser Permanente has agreed to acquire Group Health Cooperative, the Seattle-based health insurer that has nearly 130,000 customers in Eastern Washington, in a $1.8 billion transaction, Group Health announced this morning.

The transaction is pending approval by Group Health’s voting members and regulators, and Group Health said the transition could take up to a year to complete. Upon approval of the acquisition, Group Health would become fully integrated into Kaiser and operate as that  organization’s eighth region.

Group Health said the $1.8 billion in proceeds from the transaction will go toward establishing the Group Health Community Foundation, which would be focused on improving health for Washington’s families and communities.

Group Health currently has a total of nearly 590,000 enrollees. After the acquisition is completed, Kaiser will insure 11 million people who will have access to about 18,700 physicians at about 680 hospitals and medical facilities in eight states and the District of Columbia.

Group Health has offered health plans in Spokane since 1977. The organization currently has 90 physicians in Eastern Washington, serving 20 Washington counties and two in Idaho, according to data provided to the Journal of Business for its Dec. 3 Health Care Plans list