obligations of non-consolidated affiliates , mainly cpw . in addition , off-balance sheet arrangements are generally limited to the future payments under non-cancelable operating leases , which totaled $ 559 million as of may 27 , as of may 27 , 2018 , we had invested in five variable interest entities ( vies ) . none of our vies are material to our results of operations , financial condition , or liquidity as of and for the fiscal year ended may 27 , 2018 . our defined benefit plans in the united states are subject to the requirements of the pension protection act ( ppa ) . in the future , the ppa may require us to make additional contributions to our domestic plans . we do not expect to be required to make any contributions in fiscal 2019 . the following table summarizes our future estimated cash payments under existing contractual obligations , including payments due by period: .
what percent of total long-term obligations is incurred by operating leases?
( a ) amounts represent the expected cash payments of our long-term debt and do not include $ 0.5 million for capital leases or $ 85.7 million for net unamortized debt issuance costs , premiums and discounts , and fair value adjustments . ( b ) operating leases represents the minimum rental commitments under non-cancelable operating leases . ( c ) the majority of the purchase obligations represent commitments for raw material and packaging to be utilized in the normal course of business and for consumer marketing spending commitments that support our brands . for purposes of this table , arrangements are considered purchase obligations if a contract specifies all significant terms , including fixed or minimum quantities to be purchased , a pricing structure , and approximate timing of the transaction . most arrangements are cancelable without a significant penalty and with short notice ( usually 30 days ) . any amounts reflected on the consolidated balance sheets as accounts payable and accrued liabilities are excluded from the table above . ( d ) the fair value of our foreign exchange , equity , commodity , and grain derivative contracts with a payable position to the counterparty was $ 16 million as of may 27 , 2018 , based on fair market values as of that date . future changes in market values will impact the amount of cash ultimately paid or received to settle those instruments in the future . other long-term obligations mainly consist of liabilities for accrued compensation and benefits , including the underfunded status of certain of our defined benefit pension , other postretirement benefit , and postemployment benefit plans , and miscellaneous liabilities . we expect to pay $ 20 million of benefits from our unfunded postemployment benefit plans and $ 18 million of deferred compensation in fiscal 2019 . we are unable to reliably estimate the amount of these payments beyond fiscal 2019 . as of may 27 , 2018 , our total liability for uncertain tax positions and accrued interest and penalties was $ 223.6 million . significant accounting estimates for a complete description of our significant accounting policies , please see note 2 to the consolidated financial statements in item 8 of this report . our significant accounting estimates are those that have a meaningful impact .