The domestic casualty insurance market has steadily increased in size over the recent years thanks to solid growth of personal accident and liability lines of business. In 2017, the market value rose by approximately 4 percent compared to the previous year. Primary insurers continued to retain more risks with the support of their growing capacity. In particular, favorable business results in 2017 enabled them to become more confident in risk taking. Price competition in the market continued to intensify in some lines of business where loss ratios remained at low levels.
Although these primary market conditions inevitably presented challenges to the reinsurance industry, Korean Re managed to outperform the market. Our premium income from casualty lines of business increased by 6 percent as we constantly endeavored to write more business in overseas markets. We also focused on close cooperation in product development with our business partners to respond swiftly to changes in regulations and market needs.
In almost every line, our casualty business showed growth within the range of 5 to 25 percent in 2017, although premium income from personal accident business decreased by 2 percent in 2017 as we reduced our portfolio in areas where profitability deteriorated. The overseas business still accounted for a small portion of our total casualty book of business, but the pace of growth was quite noticeable at 21 percent in 2017. Liability lines of business made up the largest part of the total casualty premiums at 28 percent, followed by special risks at 26 percent and personal accident at 24 percent.
The 2018 outlook for the casualty reinsurance market in Korea is hardly different from the prior year as primary insurers look set to maintain their aggressive retention strategies. Despite such an unfavorable business condition, we will continue to focus on improving underwriting profitability through portfolio adjustments and to make swift responses to changing coverage needs in order to expand our premium volume in the local market. Globally, we will seek to broaden our business portfolio that is currently weighted toward Asia by further increasing our business in Europe and North America. In doing so, we will identify target risks and markets and maintain a conservative underwriting approach so as to achieve profitable growth.