COMMITMENTS AND CONTINGENCIES Joint and Several Liability: As provided by the Federal Home Loan Bank Act of 1932, as amended (Bank Act) or Finance Agency regulation, consolidated obligations are backed only by the financial resources of the FHLBanks. FHLBank Topeka is jointly and severally liable with the other FHLBanks for the payment of principal and interest on all of the consolidated obligations issued by the FHLBanks. The par amounts for which FHLBank Topeka is jointly and severally liable were approximately $915,106,348,000 and $946,829,735,000 as of March 31, 2017 and December 31, 2016 , respectively. Off-balance Sheet Commitments: As of March 31, 2017 and December 31, 2016 , off-balance sheet commitments are presented in Table 14.1 (in thousands): Table 14.1 03/31/2017 12/31/2016 Notional Amount Expire Within One Year Expire After One Year Total Expire Within One Year Expire After One Year Total Standby letters of credit outstanding $ 3,208,195 $ 15,656 $ 3,223,851 $ 2,995,497 $ 12,823 $ 3,008,320 Advance commitments outstanding 80,475 15,000 95,475 37,950 45,025 82,975 Commitments for standby bond purchases 413,922 780,074 1,193,996 210,349 1,002,669 1,213,018 Commitments to fund or purchase mortgage loans 116,453  116,453 90,013  90,013 Commitments to issue consolidated bonds, at par 72,500  72,500 45,000  45,000 Commitments to Extend Credit: Standby letters of credit are executed for members for a fee. A standby letter of credit is a short-term financing arrangement between the FHLBank and its member or non-member housing associate. If the FHLBank is required to make payment for a beneficiarys draw, these amounts are converted into a collateralized advance to the member. As of March 31, 2017 , outstanding standby letters of credit had terms to maturity upon issuance of the currently outstanding standby letters of credit of 4 days to 10 years with a final expiration in 2020 . As of December 31, 2016 , outstanding standby letters of credit had terms to maturity upon issuance of the currently outstan