. we determined the fair value of our long-term debt using level 2 inputs . fair values are generally estimated based on quoted market prices for identical or similar instruments . note 20 . capital stock preferred stock our second amended and restated certificate of incorporation authorizes the issuance of up to 920000 shares of preferred stock . on june 7 , 2016 , we redeemed all 80000 outstanding shares of our series a preferred stock for $ 8.3 billion