foreign exchange rate fluctuations on the translation of our income before income taxes was a benefit (detriment) of approximately $(104) million and $74 million for the years ended May 31, 2013 and 2012, respectively. 

Managing translational exposures 

To minimize the impact of translating foreign currency denominated revenues and expenses into U.S. Dollars for consolidated reporting, certain foreign subsidiaries use excess cash to purchase U.S. Dollar denominated available- for-sale investments. The variable future cash flows associated with the purchase and subsequent sale of these U.S. Dollar denominated securities at non-U.S. Dollar functional currency subsidiaries creates a foreign currency exposure that qualifies for hedge accounting under the accounting standards for derivatives and hedging. We utilize forward contracts and/or options to mitigate the variability of the forecasted future purchases and sales of these U.S. Dollar investments. The combination of the purchase and sale of the U.S. Dollar investment and the hedging instrument has the effect of partially offsetting the year-over-year foreign currency translation impact on net earnings in the period the investments are sold. Hedges of available-for- sale investments are accounted for as cash flow hedges. 

Refer to Note 6 — Fair Value Measurements and Note 17 — Risk Management and Derivatives in the accompanying Notes to the Consolidated Financial Statements for additional description of how the above financial instruments are valued and recorded as well as the fair value of outstanding derivatives at period end. 

We estimate the combination of translation of foreign currency-denominated profits from our international businesses and the year-over-year change in foreign currency related gains and losses included in other (income) expense, net had an unfavorable impact of approximately $56 million on our income before income taxes for the year ended May 31, 2013 and had an insignificant impact for the year ended May 31, 2012. 

Net investments in foreign subsidiaries 

We are also exposed to the impact of foreign exchange fluctuations on our investments in wholly-owned foreign subsidiaries denominated in a currency other than the U.S. Dollar, which could adversely impact the U.S. Dollar value of these investments and therefore the value of future repatriated earnings. We have hedged and may, in the future, hedge net investment positions in certain foreign subsidiaries to mitigate the effects of foreign exchange fluctuations on these net investments. In accordance with the accounting standards for derivatives and hedging, the effective portion of the change in fair value of the forward contracts designated as net investment hedges is recorded in the cumulative translation adjustment component of accumulated other comprehensive income. Any ineffective portion is immediately recognized in earnings as a component of other (income) expense, net. The impact of ineffective hedges was not material for any period presented. To minimize credit risk, we have structured these net investment hedges to be generally less than six months in duration. Upon maturity, the hedges are settled