american tower corporation and subsidiaries notes to consolidated financial statements related contingent consideration , and any subsequent changes in fair value using a discounted probability- weighted approach . this approach takes into consideration level 3 unobservable inputs including probability assessments of expected future cash flows over the period in which the obligation is expected to be settled and applies a discount factor that captures the uncertainties associated with the obligation . changes in these unobservable inputs could significantly impact the fair value of the liabilities recorded in the accompanying consolidated balance sheets and operating expenses in the consolidated statements of operations . as of december 31 , 2012 , the company estimates the value of all potential acquisition-related contingent consideration required payments to be between zero and $ 43.6 million . during the years ended december 31 , 2012 and 2011 , the fair value of the contingent consideration changed as follows ( in thousands ) : .
what was the improvement in non-recurring items relating to impairments from 2011 to 2012 , in millions?
items measured at fair value on a nonrecurring basis 2014during the year ended december 31 , 2012 , certain long-lived assets held and used with a carrying value of $ 5379.2 million were written down to their net realizable value of $ 5357.7 million as a result of an asset impairment charge of $ 21.5 million , which was recorded in other operating expenses in the accompanying consolidated statements of operations . during the year ended december 31 , 2011 , long-lived assets held and used with a carrying value of $ 4280.8 million were written down to their net realizable value of $ 4271.8 million , resulting in an asset impairment charge of $ 9.0 million . these adjustments were determined by comparing the estimated proceeds from sale of assets or the projected future discounted cash flows to be provided from the long-lived assets ( calculated using level 3 inputs ) to the asset 2019s carrying value . there were no other items measured at fair value on a nonrecurring basis during the year ended december 31 , 2012 . fair value of financial instruments 2014the carrying value of the company 2019s financial instruments , with the exception of long-term obligations , including the current portion , reasonably approximate the related fair value as of december 31 , 2012 and 2011 . the company 2019s estimates of fair value of its long-term obligations , including the current portion , are based primarily upon reported market values . for long-term debt not actively traded , fair value was estimated using a discounted cash flow analysis using rates for debt with similar terms and maturities . as of december 31 , 2012 , the carrying value and fair value of long-term obligations , including the current portion , were $ 8.8 billion and $ 9.4 billion , respectively , of which $ 4.9 billion was measured using level 1 inputs and $ 4.5 billion was measured using level 2 inputs . as of december 31 , 2011 , the carrying value and fair value of long-term obligations , including the current portion , were $ 7.2 billion and $ 7.5 billion , respectively , of which $ 3.8 billion was measured using level 1 inputs and $ 3.7 billion was measured using level 2 inputs . 13 . income taxes the company has filed , for prior taxable years through its taxable year ended december 31 , 2011 , a consolidated u.s . federal tax return , which includes all of its wholly owned domestic subsidiaries . for its taxable year commencing january 1 , 2012 , the company intends to file as a reit , and its domestic trss intend to file as c corporations . the company also files tax returns in various states and countries . the company 2019s state tax returns reflect different combinations of the company 2019s subsidiaries and are dependent on the connection each subsidiary has with a particular state . the following information pertains to the company 2019s income taxes on a consolidated basis. .