B737 Captain reported failure of hydraulic system in cruise. Flight continued to destination and landed safely.

Narrative

During cruise; and just prior to TOD; we received a HYD Master Caution light. We referenced the MFD SYS page to see that System A HYD quantity was at 18%; and the System A HYD pressure was still at 3000 PSI. The Caution light took us to run the QRH Non Normals Loss of SYS A. After running the QRH up to the Deferred Items; I contacted Dispatch; and then we patched in Maintenance Control. Based on our current location; weather; and the nearest suitable runway; Dispatch recommended continuing to ZZZ; and Maintenance Control agreed. I briefed the FA Purser; and that a normal landing would be the likely outcome. I then requested priority handling with ZZZ App and asked for ARFF (Airport Rescue and Firefighting) to be standing by. We then were cleared for the ILSXXR (the longest runway); and I completed the Manual Gear Extension per the QRH; and the Deferred Items Checklist. A normal landing ensued shortly after. I cleared the runway; and stopped to have ARFF check for damage or anything hindering a safe taxi to the gate. At this time I informed the passengers of our situation; and that we would taxi to the gate if given an all clear from ARFF. After getting an all clear; and prior to movement we referenced the MFD HYD SYS Page; saw HYD SYS B pressure was normal; as well as brake pressure; so we taxied to the gate. I wrote up the discrepancy via ELB; and called Maintenance Control. I then called the Chief Pilot; who called me back 30 minutes later. In retrospect I believe we did a textbook job of managing this Non-Normal. We clearly assigned roles as the FO to continue as PF; and I would continue as PM and run the QRH. We slowed the aircraft down to allow for extra time to complete the manual gear extension knowing that once it's down it cannot be retracted. So we didn't want to rush; and make any mistakes. And at no time did we violate any SOP; FAR; or ATC clearance even after requesting priority. The other thing we were given by ATC was discretion on published speed restrictions. We were clear with our intentions with regard to ATC communications; and with an ARFF visual aircraft inspection after landing. The event was far less complicated than anticipated; and a very successful outcome was a result of our company's training program fully preparing us for these types of situations. Finally; everyone was extremely helpful from ATC; ARFF; ZZZ Airport Ops; Dispatch; Maintenance Control; and the Chief Pilot.