Indonesia's foreign exchange reserves dropped to $111.47 billion at the end of November from $115.03 billion one month earlier, Bank Indonesia (BI) said on Wednesday. November's drop of $3.5 billion in reserves was mainly caused by government foreign debt payments and rupiah exchange stabilisation efforts done to put the currency in line with its fundamentals, the central bank said. The rupiah has weakened about 1.8 percent against the dollar since the US election and the central bank has said that it has intervened in both foreign exchange and bond markets.