Federal mediators involved in the Detroit’s bankruptcy proceedings announced yesterday that national and local philanthropic foundations have committed more than $300 million toward a deal that would help preserve the Detroit Institute of Art’s renowned collection by bolstering the city’s employee pension funds, the New York Times reported today. A group including the Ford Foundation, the Kresge Foundation and the John S. and James L. Knight Foundation have pledged to pool the money, which could essentially relieve the city-owned museum of its responsibility — estimated at millions of dollars — to help Detroit pay its debts in its federal bankruptcy case. As part of the plan, on which negotiators have been working quietly for months, the museum might be removed from city ownership and put under the control of the state. But mediators stopped short of saying that an agreement had been reached with state officials or with the office of Kevyn D. Orr, Detroit’s emergency manager, who had said that the museum must pay its share to help ease the city’s debt.