Korean Re reported a substantial increase in underwriting profit and a combined ratio of 98.4 percent in a year defined by massive natural catastrophe losses. Our strict underwriting policy and well-established relationships with clients and brokers helped us secure more profitable business opportunities. Our years of effort to diversify our business portfolio also showed its value in boosting our underwriting results. On the other hand, we posted weaker investment results as we booked impairment losses from our investment in KDB Life’s private equity fund that was made back in 2009.
We achieved a strong top-line growth for 2017, with gross written premiums increasing by 7.8 percent to KRW 7,208.1 billion. Our domestic business continued to perform robustly with a 6.5 percent growth, and premiums from our overseas business soared by 12.7 percent.
Premiums from domestic personal lines jumped by 9.5 percent year over year due to the effect of a rise in primary long-term insurance rates and increased writings of profitable life business. In particular, our long-term business grew by 12.6 percent, while the domestic life business expanded by 7.2 percent.
Our domestic commercial business grew by 2 percent, and the main drivers of the growth were the expansion of the mobile phone insurance market and new business covering satellite and offshore wind power risks. Still, we had to struggle with a stagnant commercial insurance market as underwriting conditions remained challenging for many lines of business. Our premium income from domestic property lines decreased by 0.4 percent to KRW 532 billion. We also saw our domestic engineering business shrink modestly to KRW 147.4 billion.
The growth of our overseas business accelerated to 12.7 percent in 2017 as we continued to see a strong increase of our international property facultative business. Our global property treaty business grew by 2.8 percent on the back of a solid expansion of our U.S. portfolio. We also recorded robust growth in most of the other lines, including engineering, aviation, life and casualty.