In In re Marilyn H. (1993) 5 Cal.4th 295, the Supreme Court explained the need to balance a parent's opportunity to reunify with his or her children against the importance of providing the children with permanent, stable homes. ( In re Marilyn H., supra, 5 Cal.4th at pp. 306, 309) If, after providing a parent with 18 months of reunification services, returning the child would be detrimental to him or her, the court must develop a permanent plan to provide stability to the child. (Marilyn H., supra, at p. 308.) After 18 months, reunification services are usually terminated and the focus of the court shifts to the needs of the child for permanency. ( Id. at p. 309.) Thus, the Supreme Court has chosen to set an 18-month limit for parents to reunify with their child before permanency planning is instituted for the child.