Year Ended December 31, 2018 AEP Texas AEPTCo APCo I&M OPCo PSO SWEPCo (in millions) Retail Revenues: Residential Revenues $ 578.9  $ —  $ 1,342.7  $ 730.0  $ 1,611.6  $ 659.0  $ 641.6  Commercial Revenues 414.7  —  580.4  485.0  835.6  394.2  483.9  Industrial Revenues 128.0  —  604.3  565.6  385.2  304.0  333.7  Other Retail Revenues 29.4  —  77.4  7.2  12.9  83.6  8.6  Total Retail Revenues (a) 1,151.0  —  2,604.8  1,787.8  2,845.3  1,440.8  1,467.8  Wholesale Revenues: Generation Revenues (b) —  —  250.4  470.5  —  36.3  216.8  Transmission Revenues (c) 313.4  816.9  82.7  23.1  58.5  40.2  108.4  Total Wholesale Revenues 313.4  816.9  333.1  493.6  58.5  76.5  325.2  Other Revenues from Contracts with Customers (d) 28.6  15.1  55.3  99.6  176.1  19.1  24.0  Total Revenues from Contracts with Customers 1,493.0  832.0  2,993.2  2,381.0  3,079.9  1,536.4  1,817.0  Other Revenues: Alternative Revenues (e) (1.3) (55.9) (23.8) (2.1) (20.8) 10.9  4.9  Other Revenues (e) 103.6  —  (1.9) (8.2) 4.3  —  —  Total Other Revenues 102.3  (55.9) (25.7) (10.3) (16.5) 10.9  4.9  Total Revenues $ 1,595.3  $ 776.1  $ 2,967.5  $ 2,370.7  $ 3,063.4  $ 1,547.3  $ 1,821.9  (a) 2018 amounts have been revised to reflect the reclassification of certain customer accounts between Retail classes. This reclassification did not impact previously reported Total Retail Revenues. Management concluded that these prior period disclosure only errors were immaterial individually and in the aggregate. (b) Amounts include affiliated and nonaffiliated revenues. The affiliated revenue for APCo was $134 million primarily relating to the PPA with KGPCo. The remaining affiliated amounts were immaterial. (c) Amounts include affiliated and nonaffiliated revenues. The affiliated revenue for AEPTCo was $646 million. The remaining affiliated amounts were immaterial. (d) Amounts include affiliated and nonaffiliated revenues. The affiliated revenue for I&M was $70 million primarily relating to barging, urea transloading and other transportation services. The remaining affiliated amounts were immaterial. (e) Amounts include affiliated and nonaffiliated revenues. Performance Obligations The purpose of the invoice practical expedient is to depict an entity’s measure of progress toward completion of the performance obligation within a contract and can only be applied to performance obligations that are satisfied over time and when the invoice is representative of services provided to date. AEP subsidiaries elected to apply the invoice practical expedient to recognize revenue for performance obligations satisfied over time as the invoices from the respective revenue streams are representative of services or goods provided to date to the customer. Performance obligations for AEP’s subsidiaries are summarized as follows: 413 AEP has performance obligations as part of its normal course of business. A performance obligation is a promise to transfer a distinct good or service, or a series of distinct goods or services that are substantially the same and have the same pattern of transfer to a customer. The invoice practical expedient within the accounting guidance for “Revenue from Contracts with Customers” allows for the recognition of revenue from performance obligations in the amount of consideration to which there is a right to invoice the customer and when the amount for which there is a right to invoice corresponds directly to the value transferred to the customer.