The California Department of Insurance approved the merger between Woodland Hills-based Zenith National Insurance Corp. and Toronto-based Fairfax Financial Holdings Limited. The acquisition of Zenith by Fairfax is expected to be completed on May 20. Fairfax Financial Holdings Limited is a financial services holding company engaged in property and casualty insurance, and reinsurance and investment management. Zenith National Insurance Corp. is a holding company engaged in workers’ compensation insurance business. Jessica Selva