Cashier Window wants my Name and ID for transactions over $2000

At my California cardroom, the first time I ever cashed out for more than $2000, they asked for my drivers license and entered my info into their system. Now every time I cash out more than $2K, they ask for either my ID or my name and log the transaction.

What do they do with this info? Do they keep records in case they get subpoenaed, or the IRS is auditing a player and wants to see their record of transactions?