Solve the Global Debt, the Code Golf way

K, 66

{(((!)."SF"$+":"\:'*+a)-+/'d)+/d:"F"$(!).'"S:,"0:/:last'a:";"\:'x}

.

k)input:0:`:ledg.txt
k){(((!)."SF"$+":"\:'*+a)-+/'d)+/d:"F"$(!).'"S:,"0:/:last'a:";"\:'x} input
US| 9439.3
FR| 2598.9
ES| 852.1
PT| 90.1
IT| 887.5
IE| 48
GR| 116.8
JP| 4817.4
DE| 2903.7
UK| 1546.2

Perl, 139 137 134 119 112

Here's another working piece of code... I will document it later.

Golfed code

With dictionary (112):

for(<>){~/:(.+);/g;$d{$c=$`}+=$1;$l=$';$d{$1}+=$2,$d{$c}-=$2while$l=~/(..):([^,]+)/g}print"$_:$d{$_}
"for keys%d

Without dictionary (137):

for($T=$t.=$_ for<>;$t=~/(..:)(.+);(.+)/g;print"$c$s\n"){$c=$1;$l=$3;$s=$2;$s-=$&while$l=~/[\d.]+/g;$s+=$1while$T=~/$c([\d.]+)(?!;|\d)/g}

Output

US:9439.3
FR:2598.9
ES:852.1
PT:90.1
IT:887.5
IE:48
GR:116.8
JP:4817.4
DE:2903.7
UK:1546.2

See it in action!

http://ideone.com/4iwyEP

Python, 211 185 183

import sys,re;t,R,F=sys.stdin.read(),re.findall,float;S=lambda e,s:sum(map(F,R(e,s)))
for m in R('(..:)(.+);(.+)',t):print m[0]+`F(m[1])+S(m[0]+'([\d.]+)(?!;|\d)',t)-S('[\d.]+',m[2])`

Output with major test case:

US:9439.300000000001
FR:2598.9
ES:852.0999999999999
PT:90.09999999999997
IT:887.5
IE:48.0
GR:116.8
JP:4817.4
DE:2903.7
UK:1546.2000000000003

(test it here: http://ideone.com/CjWG7v)