OLDWICK, N.J.--(BUSINESS WIRE)--AM Best has upgraded the Long-Term Issuer Credit Ratings (Long-Term ICRs) to “a+” (Excellent) from “a” Excellent) and affirmed the Financial Strength Rating (FSR) of A (Excellent) of American International Group, Inc.’s (AIG) property/casualty (P/C) insurance subsidiaries (collectively referred to as AIG PC). The outlook of the Long-Term ICRs has been revised to stable from positive, while the outlook of the FSR is stable. At the same time, AM Best has upgraded the Long-Term ...