S-9 Parent issued long-term debt, portions of which were loaned to its subsidiaries. Parent pays interest on the affiliated notes, but the subsidiaries accrue interest for their share of the affiliated borrowing and remit the interest to Parent. Interest income related to Parent’s loans to subsidiaries is included in Interest Income on Parent’s statements of income. Parent earned interest income on loans to subsidiaries of $2 million, $2 million and $2 million for the years ended December 31, 2019, 2018 and 2017, respectively. Interest income related to Parent’s short-term lending is included in Interest Income on Parent’s statements of income. Parent earned interest income for amounts advanced to subsidiaries of $49 million, $27 million and $16 million for the years ended December 31, 2019, 2018 and 2017, respectively. Interest expense related to Parent’s short-term borrowing is included in Interest Expense on Parent’s statements of income. Parent incurred interest expense for amounts borrowed from subsidiaries of $8 million, $11 million and $8 million for the years ended December 31, 2019, 2018 and 2017, respectively. Parent uses a commercial paper program to meet the short-term borrowing needs of subsidiaries. The program is used to fund both a Utility Money Pool, which funds the utility subsidiaries, and a Nonutility Money Pool, which funds certain nonutility subsidiaries. In addition, the program also funds, as direct borrowers, the short-term debt requirements of other subsidiaries that are not participants in either money pool for regulatory or operational reasons. The program also allows some direct borrowers to invest excess cash with Parent. Due to occasional time sensitivity and complexity of payments, Parent makes certain insurance, tax and benefit payments on behalf of subsidiary companies. Parent is then fully reimbursed by the subsidiary companies. Parent’s outstanding short-term debt was as follows: Short-term Debt Payments on Behalf of Subsidiaries 4. RELATED PARTY TRANSACTIONS Short-term Lending to Subsidiaries Affiliated Notes December 31, 2019 December 31, 2018 Type of Debt Outstanding Amount Weighted-Average Interest Rate Outstanding Amount Weighted-Average Interest Rate (in millions) (in millions) Commercial Paper $ 2,110.0 2.10% $ 1,160.0 2.96% Total Short-term Debt $ 2,110.0 $ 1,160.0