Mental health advocates and Medicaid managed care plans are cheering the Trump administration's proposal to allow Medicaid to pay for substance abuse treatment in large residential facilities, but so far it has gotten little traction in Congress, and one industry analyst said its chances of passing remain less than 50 percent. A decades-old federal law prohibits Medicaid from reimbursing care provided at facilities known as "institutions for mental disease," which are defined as residential treatment centers with more than 16...