Debt	3 Months Ended
Mar. 31, 2017
Debt Disclosure [Abstract]
Debt	Debt During the three months ended March 31, 2017, we made principal payments of $29.8 million and $1.6 million on our five-year term loan due August 2021 and our seven-year term loan due October 2020, respectively. For the three months ended March 31, 2017 and 2016, cash payments for interest were $18.0 million and $15.8 million, respectively. Included in interest expense, net, are amortization of treasury lock settlements and amortization of financing costs. For both the three months ended March 31, 2017 and 2016, amortization of treasury lock settlements was $1.4 million. For the three months ended March 31, 2017 and 2016, amortization of financing costs was $0.5 million and $0.4 million, respectively. At March 31, 2017 we had $1,647.6 million of fixed-rate senior notes and $979.3 million of variable-rate term loans outstanding. At March 31, 2017 the fair value of our fixed-rate debt was estimated to be $1,721.9 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 2016 Annual Report on Form 10-K. The fair value of our variable-rate term debt approximates the carrying amount as our cost of borrowing is variable and approximates current market rates. For more information on our long-term debt and interest rates on that debt, see Note 9, Debt, of the Notes to Consolidated Financial Statements in "Part II, Item 8. Financial Statements and Supplementary Data" of our 2016 Annual Report on Form 10-K.

Debt

During the three months ended March 31, 2017, we made principal payments of $29.8 million and $1.6 million on our five-year term loan due August 2021 and our seven-year term loan due October 2020, respectively. For the three months ended March 31, 2017 and 2016, cash payments for interest were $18.0 million and $15.8 million, respectively.

Included in interest expense, net, are amortization of treasury lock settlements and amortization of financing costs. For both the three months ended March 31, 2017 and 2016, amortization of treasury lock settlements was $1.4 million. For the three months ended March 31, 2017 and 2016, amortization of financing costs was $0.5 million and $0.4 million, respectively.

At March 31, 2017 we had $1,647.6 million of fixed-rate senior notes and $979.3 million of variable-rate term loans outstanding. At March 31, 2017 the fair value of our fixed-rate debt was estimated to be $1,721.9 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 2016 Annual Report on Form 10-K. The fair value of our variable-rate term debt approximates the carrying amount as our cost of borrowing is variable and approximates current market rates.

For more information on our long-term debt and interest rates on that debt, see Note 9, Debt, of the Notes to Consolidated Financial Statements in "Part II, Item 8. Financial Statements and Supplementary Data" of our 2016 Annual Report on Form 10-K.