In December 2016, we entered into seven floating-to-fixed interest rate swap agreements to manage our risk from interest rate fluctuations associated with the floating-rate Term Loan Facility. The swap agreements became effective on February 3, 2017 with an aggregate notional amount of $1.50 billion. Two swap agreements matured in 2018, one agreement matured in 2019, and one agreement matured in February 2020. The remaining three swap agreements in effect as of December 31, 2020 have an aggregate notional amount of $1.05 billion and mature over the next two years. On a quarterly basis, we net settle with the counterparty for the difference between the fixed rate specified in each swap agreement, ranging from 1.7625% to 1.9040%, and the variable rate based upon the three-month LIBOR as applied to the notional amount of the swap.

In December 2018, we entered into four additional floating-to-fixed interest rate swap agreements with an aggregate notional amount of $1.35 billion and a maturity date of November 3, 2023. These swap agreements are forward-starting, and as of December 31, 2020, two swap agreements, with an aggregate notional amount of $300 million, were effective. The remaining swap agreements become effective each year thereafter to coincide with the maturity dates of the outstanding December 2016 swap agreements. On a quarterly basis, we net settle with the counterparty for the difference between the fixed rate specified in each swap agreement, ranging from 2.7350% to 2.7490%, and the variable rate based upon the three-month LIBOR as applied to the notional amount of the swap.

In November 2017, we entered into three forward contracts. Under the terms of these contracts, we sold a total of £120 million at an average rate of 1.34378 British pound sterling to U.S. dollar and received $161.3 million. These contracts settled on November 30, 2018 and we received a final net payment of $7.9 million.

In November 2018, we entered into one foreign currency forward contract. Under the terms of the contract, we sold £75 million at a rate of 1.3002 British pound sterling to U.S. dollar and received $97.5 million. This contract settled on November 29, 2019 and we received a final net payment of $0.8 million.

In November 2019, we entered into two foreign currency net-zero cost collar contracts with an aggregate notional amount of £100 million and a maturity date of November 30, 2020. Under the terms of the contracts, the British pound sterling to U.S. dollar exchange rate floats between 1.2375 and 1.3475. On March 26, 2020, we settled one of these contracts, with an aggregate notional amount of £50 million, and we received a final net payment of $1.9 million and on November 19, 2020, we settled the remaining contract, with an aggregate notional amount of £50 million, and we made a final net payment of $0.2 million.

During 2020, we entered into a series of foreign currency contracts to manage our exposure to movements in the British pound sterling, Euro, and Mexican peso. These contracts had three-month terms and settled at various dates throughout the year, which resulted in the company making aggregate payments of $5.4 million. As of December 31, 2020, there was no notional amount outstanding related to these contracts.

During the fourth quarter of 2020, we entered into two foreign currency forward contracts. Under the terms of these contracts, on November 30, 2021, we will sell a total of £80 million at an average rate of 1.3388 British pound sterling to U.S. dollar and receive $107.1 million.

We entered into a fixed price power contract for a London data center in September 2015 as part of our price risk management strategy and accounted for it as a derivative that did not qualify for the normal purchases normal sales exception. The contract ended in September 2018 and we executed a new contract with a term of October 2018 through September 2021 that met the normal purchases normal sales exception. Therefore, as of December 31, 2019 and 2020, we do not have any power contracts recorded at fair value on the Consolidated Balance Sheets.


		December 31, 2019				December 31, 2020
(In millions)		Assets		Liabilities		Assets		Liabilities
Derivatives not designated as hedging instruments	Location


Interest rate swaps	Other current liabilities	$	—	$	3.5	$	—	$	—
Interest rate swaps	Other non-current liabilities	—		33.1		—		—


Foreign currency contracts	Other current assets	1.4		—		—		—
Foreign currency contracts	Other current liabilities	—		2.9		—		1.7

Total		$	1.4	$	39.5	$	—	$	1.7

Derivatives designated as hedging instruments	Location


Interest rate swaps	Other current liabilities	$	—	$	—	$	—	$	22.6
Interest rate swaps	Other non-current liabilities	—		—		—		64.4
Total		$	—	$	—	$	—	$	87.0

For financial statement presentation purposes, we do not offset assets and liabilities under master netting arrangements and all amounts above are presented on a gross basis. The following table, however, is presented on a net asset and net liability basis:


	December 31, 2019						December 31, 2020
(In millions)	Gross Amounts on Balance Sheet		Effect of Counter-Party Netting		Net Amounts		Gross Amounts on Balance Sheet		Effect of Counter-Party Netting		Net Amounts
Assets

Foreign currency contracts	$	1.4	$	(1.4)	$	—	$	—	$	—	$	—
Total	$	1.4	$	(1.4)	$	—	$	—	$	—	$	—

Liabilities
Interest rate swaps	$	36.6	$	—	$	36.6	$	87.0	$	—	$	87.0
Foreign currency contracts	2.9		(1.4)		1.5		1.7		—		1.7
Total	$	39.5	$	(1.4)	$	38.1	$	88.7	$	—	$	88.7

The effect of our derivatives and their location on the Consolidated Statements of Comprehensive Loss for the years ended December 31, 2018, 2019 and 2020 was as follows:


		Year Ended December 31,
(In millions)		2018		2019		2020
Derivatives not designated as hedging instruments	Location
Interest rate swaps	Interest expense	$	1.8	$	(51.6)	$	(3.2)
Power contracts	Cost of revenue	(0.5)		—		—
Foreign currency contracts	Other income (expense), net	11.2		(1.6)		(3.8)

Derivatives designated as hedging instruments	Location
Interest rate swaps	Interest expense	$	—	$	—	$	(11.0)

Interest expense was $281.1 million, $329.9 million and $268.4 million for the years ended December 31, 2018, 2019 and 2020, respectively. As of December 31, 2020, the amount of cash flow hedge losses included within "Accumulated other comprehensive income (loss)" that is expected to be reclassified as an increase to "Interest expense" over the next 12 months is approximately $19.6 million. See Note 17, "Accumulated Other Comprehensive Income (Loss)," for information regarding changes in fair value of our derivatives designated as hedging instruments.

We have agreements with interest rate swap counterparties that contain a provision whereby if we default on any of our material indebtedness, then we could also be declared in default of our interest rate swap agreements. As of December 31, 2020, our interest rate swap agreements with an aggregate fair value of $87.0 million were in a net liability position.