Find next transaction date for same customer

I have a table of transactions that include Date and Customer ID. How can I find for a transaction, the next transaction for the same customer?

For example, a customer might have several transactions over several dates. If I look at any one of those transactions, I need to find the very next dated transaction.

Date-----Next Date
1/1/19--1/15/19
1/15/19-2/2/19
2/2/19--2/3/19
2/3/19--(blank)

Thank you.

Instead of "date" and "customer number", your example shows "date" and "next date". This is not really helpful