In 2015, British Petroleum agreed to pay $18.7 billion to a fund established by the U.S. government to settle claims related to the Deepwater Horizon oil spill in the Gulf of Mexico. If the agreement with the government was structured as a payment in settlement of a legal dispute, rather than as a fine or penalty, what was the after-tax cost to BP of the payment? (Use 6 zeroes and 3 commas in your answer).