The use of a portion of our $1,235 U.S. federal NOL as of December 31, 2014 is subject to limitation due to the change in  ownership of our stock upon emergence from bankruptcy. Generally, the application of the relevant Internal Revenue Code  (IRC) provisions will release the limitation on $84 of pre-change NOLs each year, allowing pre-change losses to offset post- change taxable income. Through further evaluation and audit adjustment, and after considering U.S. taxable income in 2014,  we estimate that $677 of our U.S. federal NOLs remains subject to limitation as of December 31, 2014.The remainder of our  U.S. federal NOLs represents a combination of post-change NOLs and pre-change NOLs on which the limitation has been  released. However, there can be no assurance that trading in our shares will not ef fect another change in ownership under the  IRC which would further limit our ability to utilize our available NOLs. Unrecognized tax benefits  — Unrecognized tax benefits are the dif ference between a tax position taken, or expected to be  taken, in a tax return and the benefit recognized for accounting purposes. Interest income or expense, as well as penalties  relating to income tax audit adjustments and settlements, are recognized as components of income tax expense or benefit.  Interest of $6 and $5 was accrued on the uncertain tax positions as of  December 31, 2014 and 2013. Reconciliation of gross unrecognized tax benefits — 2014 2013 2012 Balance, beginning of period $ 101 $ 108 $ 46 Decrease related to expiration of statute of limitations (3 ) (7 ) (9 ) Increase (decrease) related to prior years tax positions (6 ) 63 Increases related to current year tax positions 25 6 8 Decrease related to settlements (14 ) Balance, end of period $ 109 $ 101 $ 108 We anticipate that our gross unrecognized tax benefits will decrease by  $13 in the next twelve months upon the expected  completion of examinations in various jurisdictions.The settlement of these matters will not impact the ef fective tax rate.  Gross unrecognized tax benefits of  $61 would impact the effective tax rate if recognized. If other open matters are settled with  the IRS or other taxing jurisdictions, the total amounts of unrecognized tax benefits for open tax years may be modified. Note 18. Other Income, Net 2014 2013 2012 Interest income $ 15 $ 25 $ 24 Government grants and incentives 4 3 8 Foreign exchange gain (loss) 11 (5 ) (15 ) Strategic transaction expenses (3 ) (4 ) (10 ) Write-off of deferred financing costs (4 ) Gain on sale of marketable securities 9 Recognition of unrealized gain on payment-in-kind note receivable 2 5 Insurance and other recoveries 2 13 2 Impairment of long-lived assets (2 ) Other 17 13 12 Other income, net $ 48 $ 55 $ 19 Interest income decreased from 2013 as a result of selling our payment-in-kind note receivable during the first quarter of  2014. The receipt of a payment on our payment-in-kind note receivable during the second quarter of 2013 resulted in the  recognition of a portion of the related unrealized gain that arose following the valuation of the note receivable below its  callable value at emergence from bankruptcy. The subsequent sale of the payment-in-kind note receivable during the first  quarter of 2014 resulted in the recognition of the remaining unrealized gain. See Note 14 for additional information. During 2013 we recorded $3 of interest income as a result of a favorable legal ruling related to recovery of gross receipts  tax paid in Brazil in earlier periods. Foreign exchange gains and losses on cross-currency intercompany loan balances that are not considered permanently  invested are reported above. Foreign exchange gains and losses on intercompany loans that are permanently invested are  reported in OCI. As discussed in Note 1 above, effective March 31, 2014, we ceased using the of ficial exchange rate of 6.3 and  began using the SICAD rate, which was 10.7 bolivars per U.S. dollar (as published by the Central Bank of  Venezuela) at March  81