B767 First Officer reported a hydraulic malfunction during cruise flight. The flight returned to the departure airport and landed safely.

Narrative

At approximately XA:35 local time; I was woken up from my break as relief pilot. I was told by the Flight Attendant that there was a hydraulic leak and I was needed in the cockpit. I immediately returned to the cockpit and asked how I could help. The Captain (PM) and FO (PF) were in the process of diverting and had already accomplished most the actions in the FOM diversion planning guide. Prior to that they had accomplished the R HYD QTY non normal checklist. There was approximately 0.47rf showing in the right hydraulic reservoir. The associated pumps were secured and there was negligible pressure (approx. 50 psi) residual in that system. No further loss of fluid was occurring. They briefed me further that they had initiated a SATCOM call with Dispatch and Maintenance Control; and based on weather and the stability of the situation; all parties agreed a return to ZZZ was the best course of action at that time. All of the information I received was pertinent; concise; and relevant. The communications were some of the best I have experienced in my years with the company.I reviewed the steps taken in the R HYD QTY checklist. I looked further into the Flight Manual at the possibility of a loss of all fluid in the right hydraulic system; when the pumps were turned back on during the approach; as directed by the checklist. If this happened; it would produce a R HYD SYS PRESS annunciation. I looked at the steps in that checklist; and which other systems would be affected. The Captain joined me in this review. It didn't look like braking would be affected. We would not be able to Autoland; but the weather was at or above CAT (Category) 1 minimums; so this was not limiting; but worthy of discussion. The Captain asked that I keep that checklist ready and pulled up in the event that we might need to run it during the approach. I reviewed all of the steps several times; thoroughly. We discussed the idea of [requesting priority handling]; but we all agreed that the current situation was stable; there was not imminent danger; and we did not require immediate assistance. We agreed that any further degradation would likely merit [requesting priority handling].We discussed the weather at ZZZ; as the conditions were IFR. Over the course of the diversion (approximately 2 hours); the TAF improved up to 600 OVC (overcast) and 1-1/2 miles visibility. There was a weather system over the area; and conditions at ZZZ1; ZZZ2; and ZZZ3 were all worse. This reinforced the decision to return to ZZZ.There were several conversations with the purser about the situation; overall passenger condition; and passenger perception of what was going on. The passengers were all fairly calm throughout the diversion. The Captain made a brief PA describing what had happened and that in the essence of safety we would need to return to ZZZ. We were told by the flight attendants that this message was received well.We received a fairly straightforward reroute for the ZZZZZ arrival. Multiple discussions occurred before formal descent brief about possible changes to our situation and appropriate courses of action. The descent brief was thorough and complete. We set up and planned for the ILS XXR; and a flaps 25 landing. Approach and REF speeds were 155 and 150. We had excess runway available even in the event of a loss of all pressure. Dispatch sent us a message with landing distance that showed the same thing we had determined from the non-normal landing distance tables in the flight manual.The descent checklist (deferred items) was accomplished and descent was accomplished normally at normal airspeeds. When we checked in with the Approach Controller we did advise that would not like short vectors to the approach; as this would give us time to configure early and determine if the fluid loss would continue and if so; how significantly. The PF configured prior to LOC intercept at 2000 ft. We turned the associated hydraulic pumps on and no further loss of fluid occurred. A normal ILS was accomplished. We broke out of the clouds at approximately 800 feet MSL. We saw the runway shortly after that. The approach was stable and a normal touchdown occurred. At some point in the landing rollout and taxing clear; the right hydraulic quantity dropped to approximately 0.35rf; but it stabilized there and never went to zero. We taxied to Gate XX and accomplished normal checklists; completing the flight. We debriefed and discussed CRM/TEM (Threat and Error Management) skills. In an overall way; looking back; we were pleased with the safe outcome and the methods we used. I believe leadership effectiveness was key to this situation. The Captain listened thoroughly when either FO had input or ideas. We discussed all of our actions before choosing what we would do; and there was a high level of professionalism the entire time. When the cockpit debrief was complete; we opened the door; briefed the maintenance technicians who were waiting at the gate for us and turned the aircraft over to maintenance.