Debt

3 Months Ended

Mar. 31, 2020

Debt Disclosure [Abstract]

Debt

11. Debt

For both the three months ended March 31, 2020 and 2019, cash payments for interest were $7.3 million.

Included in interest expense, net is the amortization of financing costs, and, for 2019 only, the amortization of treasury lock settlements. The remaining balances of the treasury lock settlements were written off in connection with the debt refinancing completed in December 2019. For the three months ended March 31, 2020 and 2019, amortization of financing costs was $0.5 million and $0.7 million, respectively. For the three months ended March 31, 2019, amortization of treasury lock settlements was $1.3 million.

At March 31, 2020, we had $2,493.2 million of fixed-rate senior notes outstanding. The fair value of our fixed-rate debt was estimated to be $2,615.4 million. The difference between the book value and fair value is due to the difference between the period-end market interest rate and the stated rate of our fixed-rate debt. We estimated the fair value of our fixed-rate debt using quoted market prices (Level 2 inputs) within the fair value hierarchy, which is further defined in Note 2, Summary of Significant Accounting Policies, of the Notes to Consolidated Financial Statements in "Part II, Item 8. Financial Statements and Supplementary Data" of our 2019 Annual Report on Form 10-K.

For more information on our long-term debt and interest rates on that debt, see Note 11, Debt, of the Notes to Consolidated Financial Statements in "Part II, Item 8. Financial Statements and Supplementary Data" of our 2019 Annual Report on Form 10-K.