Details of interest expense are as follows:



	Year ended December 31,
	2016			2015			2014
	(in millions)
Interest on borrowings⁽¹⁾	$	303		$	267		$	238
Fees on financing agreements^(1)(2)(3)	59			17			11
Interest on tax liabilities	4			3			3
Interest capitalized	(166		)	(154		)	(74		)
Interest expense	$	200		$	133		$	178

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⁽¹⁾	See Note 12—Financing Agreements for additional information.

⁽²⁾

Fees on financing agreements for the year ended December 31, 2016 includes $28 million of fees related to the termination of the tranche B commitment under the bridge credit agreement as a result of the termination of the Combination Agreement. Fees on financing agreements for the year ended December 31, 2015 includes $6 million of accelerated amortization of deferred fees related to the termination in September 2015 of the tranche A commitment under the bridge credit agreement. See Note 4—Acquisitions and Divestitures additional information.

⁽³⁾

Fees on financing agreements for the year ended December 31, 2016 includes $9 million of accelerated amortization of deferred fees related to the payment of the Private Senior Notes in November 2016, $2 million of accelerated amortization of deferred fees related to the July 2016 Credit Agreement Amendment, which reduced the Revolving Credit Facility to $1.5 billion from $2.0 billion, and $4 million of accelerated amortization of deferred fees related to the November 2016 Credit Agreement Amendment, which reduced the Revolving Credit Facility to $750 million from $1.5 billion. See Note 12—Financing Agreements for additional information.