From the New York Times:
A review of personal financial disclosures that Mr. Cruz filed later with the Senate does not find a liquidation of assets that would have accounted for all the money he spent on his campaign. What it does show, however, is that in the first half of 2012, Ted and Heidi Cruz obtained the low-interest loan from Goldman Sachs, as well as another one from Citibank. The loans totaled as much as $750,000 and eventually increased to a maximum of $1 million before being paid down later that year. There is no explanation of their purpose.
As discussed in Episode 0005.