what was the difference in principal amount of senior notes due 2022 compared to senior notes due 2023 , in millions?
table of contents ended december 31 , 2015 and 2014 , respectively . the increase in cash provided by accounts payable-inventory financing was primarily due to a new vendor added to our previously existing inventory financing agreement . for a description of the inventory financing transactions impacting each period , see note 6 ( inventory financing agreements ) to the accompanying consolidated financial statements . for a description of the debt transactions impacting each period , see note 8 ( long-term debt ) to the accompanying consolidated financial statements . net cash used in financing activities decreased $ 56.3 million in 2014 compared to 2013 . the decrease was primarily driven by several debt refinancing transactions during each period and our july 2013 ipo , which generated net proceeds of $ 424.7 million after deducting underwriting discounts , expenses and transaction costs . the net impact of our debt transactions resulted in cash outflows of $ 145.9 million and $ 518.3 million during 2014 and 2013 , respectively , as cash was used in each period to reduce our total long-term debt . for a description of the debt transactions impacting each period , see note 8 ( long-term debt ) to the accompanying consolidated financial statements . long-term debt and financing arrangements as of december 31 , 2015 , we had total indebtedness of $ 3.3 billion , of which $ 1.6 billion was secured indebtedness . at december 31 , 2015 , we were in compliance with the covenants under our various credit agreements and indentures . the amount of cdw 2019s restricted payment capacity under the senior secured term loan facility was $ 679.7 million at december 31 , 2015 . for further details regarding our debt and each of the transactions described below , see note 8 ( long-term debt ) to the accompanying consolidated financial statements . during the year ended december 31 , 2015 , the following events occurred with respect to our debt structure : 2022 on august 1 , 2015 , we consolidated kelway 2019s term loan and kelway 2019s revolving credit facility . kelway 2019s term loan is denominated in british pounds . the kelway revolving credit facility is a multi-currency revolving credit facility under which kelway is permitted to borrow an aggregate amount of a350.0 million ( $ 73.7 million ) as of december 31 , 2015 . 2022 on march 3 , 2015 , we completed the issuance of $ 525.0 million principal amount of 5.0% ( 5.0 % ) senior notes due 2023 which will mature on september 1 , 2023 . 2022 on march 3 , 2015 , we redeemed the remaining $ 503.9 million aggregate principal amount of the 8.5% ( 8.5 % ) senior notes due 2019 , plus accrued and unpaid interest through the date of redemption , april 2 , 2015 . inventory financing agreements we have entered into agreements with certain financial intermediaries to facilitate the purchase of inventory from various suppliers under certain terms and conditions . these amounts are classified separately as accounts payable-inventory financing on the consolidated balance sheets . we do not incur any interest expense associated with these agreements as balances are paid when they are due . for further details , see note 6 ( inventory financing agreements ) to the accompanying consolidated financial statements . contractual obligations we have future obligations under various contracts relating to debt and interest payments , operating leases and asset retirement obligations . our estimated future payments , based on undiscounted amounts , under contractual obligations that existed as of december 31 , 2015 , are as follows: .

|  | Payments Due by Period |
| :--- | :--- |
| (in millions) | Total | < 1 year | 1-3 years | 4-5 years | > 5 years |
| Term Loan<sup>(1)</sup> | $1,703.4 | $63.9 | $126.3 | $1,513.2 | $— |
| Kelway Term Loan<sup>(1)</sup> | 90.9 | 13.5 | 77.4 | — | — |
| Senior Notes due 2022<sup>(2)</sup> | 852.0 | 36.0 | 72.0 | 72.0 | 672.0 |
| Senior Notes due 2023<sup>(2)</sup> | 735.1 | 26.3 | 52.5 | 52.5 | 603.8 |
| Senior Notes due 2024<sup>(2)</sup> | 859.7 | 31.6 | 63.3 | 63.3 | 701.5 |
| Operating leases<sup>(3)</sup> | 143.2 | 22.5 | 41.7 | 37.1 | 41.9 |
| Asset retirement obligations<sup>(4)</sup> | 1.8 | 0.8 | 0.5 | 0.3 | 0.2 |
| Total | $4,386.1 | $194.6 | $433.7 | $1,738.4 | $2,019.4 |

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a = 852.0 - 735.1