FUNDS RECEIVABLE AND CUSTOMER ACCOUNTS AND INVESTMENTS - Estimated Fair Values of Investments Classified as Available for Sale Included within Funds Receivable and Customer Accounts by Date of Contractual Maturity (Details) $ in Millions	Dec. 31, 2020 USD ($)
Amortized Cost
One year or less	$ 17,416
After one year through five years	4,168
Total	21,584
Fair Value
One year or less	17,421
After one year through five years	4,174
Total	$ 21,595