	March 31, 2021		December 31, 2020
Assumed gathering, processing and transportation contracts	$	482	$	—
Pension and post retirement benefit obligations		225		243
Restructuring and transaction costs		130		137
Estimated future obligation under a performance guarantee		128		—
Commodity derivatives		122		5
Other		182		166
Total other long-term liabilities	$	1,269	$	551

Devon assumed fixed gathering, processing and transportation contracts in the Merger and recognized a liability related to the difference in the contractual and market rates of these contracts as of the date of the Merger. The terms of the contracts extend through 2038 and all relate to the Delaware Basin. This difference will be recognized as a reduction to production expenses as the associated reserves are produced over the life of the respective contracts. In the first quarter of 2021, Devon recognized $8 million of non-cash amortization of these liabilities as a reduction of production expenses in the consolidated statement of comprehensive earnings.

Additionally, in the Merger, Devon assumed a future obligation under a performance guarantee related to gathering and processing commitments for assets WPX sold in 2018 in which the purchaser of those assets is now not expected to have the financial ability to satisfy the obligations. As of March 31, 2021, Devon has recorded a $164 million liability for the estimated potential exposure based on probability-weighted cash flows for the remainder of the contract term of five years. Of the $164 million, $128 million is included in other long-term liabilities and $36 million is included in other current liabilities on the consolidated balance sheets as of March 31, 2021.