Regional Jet 900 (CRJ900)
Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Situational Awareness; Confusion
Deviation - Track / Heading All Types; Inflight Event / Encounter Wake Vortex Encounter
Air Traffic Control Issued New Clearance; Flight Crew Took Evasive Action; Flight Crew Requested ATC Assistance / Clarification
Procedure; Aircraft; Environment - Non Weather Related
Beginning descent into JFK from 20;000 ft. we were cleared to cross CCC at 12;000 ft. Seat belt sign was off as we were in calm clear conditions; typically passing 18;000 ft. arrival PA to pax would be made and seatbelt sign illuminated. There was no traffic in our vicinity depicted on TCAS nor did ATC advise us of any. Suddenly the aircraft began to roll abruptly to the left and right as well as pitching (less abruptly) down. The pilot flying disconnected the autopilot and stabilized the aircraft's flight path; the pilot monitoring immediately illuminated the seatbelt sign and contacted ATC. He asked if they were 'Following anything heavy' to which ATC informed them they were more than 20 miles in trail of a Boeing 777.  The Pilot Monitoring informed ATC that they had experienced serious wake turbulence and asked for a vector off course to mitigate the situation. Once stable; the Captain made a PA to the passengers informing them of the cause of the disturbance and followed up with a call to the flight attendants to verify they and everyone else were OK.  The voice of a different Controller then came on the radio and asked if any injuries had been sustained of if assistance was needed; to which the Captain replied no.  After the situation was under control; the Captain advised that the aircraft could return to course and continue the flight as planned.  Unexpected wake turbulence with adequate spacing between aircraft.
CRJ-900 Captain reported encountering wake turbulence on arrival into JFK more than 20 miles in trail of a B777.