How NSA intercepts the traffic beyond ssl

According to this link,

when you send an email or otherwise use the internet, the data travels from your computer, through telecommunication companies' wires and fiber optics networks, to your intended recipient. To intercept these communications, the government installed devices known as “fiber-optic splitters” in many of the main telecommunication junction points in the United States (like the AT&T facility in San Francisco). These splitters make exact copies of the data passing through them: then, one stream is directed to the government, while the other stream is directed to the intended recipients.

After that they use Deep Packet Inspection to inspect the data. But I dont understand how NSA spies users whom are using ssl enabled communication. How It works over ssl? I dont think they can decrypt the communication. Any Logical explanations?