2013 ANNUAL REPORT 29 Sustainable Resources Property Investments Intangible Assets Goodwill Goodwill decreased by $902 million from December 31, 2012 to $1,588 million, primarily due to the elimination of $591 million  of goodwill within our Pacific Northwest timberlands, which were sold during 2012 and a reduction in non-U.S. dollar balances  from negative currency revaluation. During 2012 goodwill decreased due to the impact of lower exchange rates on the translated  value of goodwill in our Brazilian residential operations, and the sale of a property services business.  Intangible assets relate primarily to concession arrangements within our infrastructure operations, in particular our Australian  coal terminal ($2.2 billion) and Chilean toll roads ($1.3 billion). Intangible assets declined by $726 million during 2013 due to  amortization and the impact of lower exchange rates on intangible assets within non-U.S. operations. Intangibles increased by  $1.7 billion during 2012 as the acquisition of the Chilean toll roads during the year gave rise to $1.4 billion of intangibles at the  year end and amortization was offset by foreign currency appreciation. GGP owns a large U.S. retail mall portfolio which at year end was valued on a discounted cash flow basis using a discount rate  of 7.6%, a terminal capitalization rate of 5.8%, and an investment horizon of 10 years.  Investments increased by $2.3 billion in 2012, reflecting our share of their net income, in particular fair value changes, and we  acquired several equity accounted investments within our infrastructure operations. Investments increased by $1.7 billion during 2013 and by $2.3 billion during 2012. The majority of the increases in 2013 include  our follow-on investment in GGP ($995 million) and in our South American toll roads. These increases were partially offset by  valuation charges against the carrying value of our natural gas pipeline investment and GGP, as well as lower foreign currency  valuation. Our largest investment is a 28% interest in General Growth Properties (“GGP”) with a carrying value at December 31, 2013  of $6.0 billion. Certain of our investee entities, including GGP, carry their assets at fair value, in which case we record our  proportionate share of any fair value adjustments. Changes in the carrying values of equity accounted investments typically  relate to the purchase or sale of shares and our share of their comprehensive income, including fair value changes, and are  reduced by our share of any dividends or other distributions. Our sustainable resources key valuation assumptions include a weighted average discount and terminal capitalization rate of  6.9% (2012 – 6.2%), and terminal valuation dates of 20 to 28 years (2012 – 20 to 90 years). Timber and agricultural asset prices  were based on a combination of forward prices available in the market and the price forecasts. The decrease in terminal valuation  dates was a result of the sale of our Pacific Northwest timber operations. Sustainable resources declined to $0.5 billion at December 31, 2013. The $3 billion reduction is due almost entirely to the sale  of our Pacific Northwest and Western Canadian timber operations. We carry our sustainable resources assets at fair value, and  revalue them quarterly with adjustments recorded as fair value changes in our statement of operations. We recorded modest  fair value gains during each of 2013 and 2012. During 2012 our sustainable resource assets increased due to an increase in the  valuation of these assets.  Key valuation assumptions for our hospitality operations included a weighted average discount rate of 10.5% (2012 – 9.9%),  terminal capitalization rate of 7.6% (2012 – 7.5%), and investment horizon of 7 years (2012 – 5 years). Property PP&E primarily consists of hotel and resort operations, which increased by $74 million. The largest change was the  increase in the valuation of a resort operation which increased in value based on increased expected cash flows. We acquired a  controlling interest in a large resort property in 2012 which gave rise to a $2.5 billion increase in property PP&E in that year.