ACR MISSES XING RESTRICTION ON DSCNT. REACHES PROPER ALT IN 2-3 MI.

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OUR FLT WAS ENRTE DTW-BWI AT FL370. CAPT WAS FLYING. WE WERE CLRED DIRECT LIZZIO INTERSECTION (I HAD RADIAL (101 DEG) AND DME (34) OFF OF NEW VOR SET UP AS A BACKUP.) ATC CLRED US TO FL350. WE DSNDED AND LEVELED. RECEIVED A FREQ CHANGE; THEN RECEIVED A CLRNC TO CROSS LIZZIO AT FL270. CAPT PROGRAMMED THE XING RESTRICTION INTO THE FMC CORRECTLY; HE PLANNED TO WAIT UNTIL WE REACHED THE TOP OF DSCNT POINT SHOWN ON THE FMC DSCNT PAGE TO BEGIN OUR IDLE PWR DSCNT. PRIOR TO THE FMC COMPUTED TOD POINT; ATC REQUESTED THAT WE BEGIN OUR DSCNT. CAPT USED V/S MADE OF AUTOPLT AND STARTED DOWN. (IF HE HAD ENGAGED THE 'CAPTURE' MODE/FUNCTION ON THE DSCNT PAGE; WE WOULD HAVE BEGUN A 1000 FPM DSCNT UNTIL WE CAPTURED THE PROFILE.) WHILE IN THE DSCNT CAPT CHKED OUR PROFILE ON DSCNT PAGE OF FMC - WE'D GOTTEN BEHIND (IT SHOWED US HIGH) ON THE PROFILE. CAPT EXTENDED THE SPD BRAKES; INCREASED OUR SPD AND OUR RATE OF DSCNT. FMC SHOWED THAT WE CROSSED LIZZIO AT FL279. (WE REACHED FL270 APPROX 2-3 MI E OF LIZZIO INTERSECTION.) NO TFC ADVISORIES WERE ISSUED BY TCASII IN OUR DSCNT; AND ATC DID NOT QUESTION OUR ALT OVER LIZZIO. IN RETROSPECT; THE CAPT KNEW WHAT OUR XING RESTRICTION WAS; PROGRAMMED THE FMC CORRECTLY; MONITORED OUR PROGRESS IN THE DSCNT - HE JUST WAITED TOO LONG TO CORRECT OUR PROFILE. THIS OCCURRED ON THE LAST LEG OF OUR 3 DAY TRIP. PRIOR TO OUR DEP ON THE FIRST DAY OF THE TRIP; THE CAPT INFORMED ME THAT HE LIKED TO TREAT THE 'CAPTURE' BUTTON ON THE DSCNT PAGE AS IF IT WERE BROKEN - HE LIKED TO MAKE IDLE PWR DSCNT.