rates depending on the asset and (4) a tax rate. These assumptions are consistent with those hypothetical market participants would use. Since we are required to make estimates and assumptions when evaluating goodwill and indefinite-lived intangible assets for impairment, the actual amounts may differ materially from these estimates.  

 

Changes in assumptions or circumstances could result in impairment. Factors which could cause impairment include, but are not limited to, (1) negative trends in our market capitalization, (2) an increase in fuel prices, (3) declining passenger mile yields, (4) lower passenger demand as a result of the weakened U.S. and global economy, (5) interruption to our operations due to an employee strike, terrorist attack, or other reasons, 

(6) changes to the regulatory environment and (7) consolidation of competitors in the airline industry.  

 

Goodwill. As of December 31, 2011 and 2010 , our goodwill balance was $9.8 billion . In evaluating goodwill for impairment, we estimate the fair value of our reporting unit by considering market capitalization and other factors if it is more likely than not that the fair value of our reporting unit is less than its carrying value. If the reporting unit's fair value exceeds its carrying value, no further testing is required. If, however, the reporting unit's carrying value exceeds its fair value, we then determine the amount of the impairment charge, if any. We recognize an impairment charge if the carrying value of the reporting unit's goodwill exceeds its estimated fair value.  

 

Identifiable Intangible Assets. Our identifiable intangible assets had a net carrying amount of $4.8 billion at December 31, 2011 . Indefinitelived assets are not amortized and consist primarily of routes, slots, the Delta tradename and assets related to SkyTeam. Definite-lived intangible assets consist primarily of marketing agreements and contracts and are amortized on a straight-line basis or under the undiscounted cash flows method over the estimated economic life of the respective agreements and contracts.  

 

We perform the impairment test for indefinite-lived intangible assets by comparing the asset's fair value to its carrying value. Fair value is estimated based on (1) recent market transactions, where available, (2) the lease savings method for certain airport slots (which reflects potential lease savings from owning the slots rather than leasing them from another airline at market rates), (3) the royalty method for the Delta tradename (which assumes hypothetical royalties generated from using our tradename) or (4) projected discounted future cash flows. We recognize an impairment charge if the asset's carrying value exceeds its estimated fair value.  

 

Long-Lived Assets  

 

Our flight equipment and other long-lived assets have a recorded value of $20.2 billion at December 31, 2011 . This value is based on various factors, including the assets' estimated useful lives and salvage values. We record impairment losses on flight equipment and other long-lived assets used in operations when events and circumstances indicate the assets may be impaired and the estimated future cash