The number is simply too large. You must be running on a 32-bit operating system.
On a 32-bit system, the largest an integer can be is 2147483647 (just over 2 billion).
On a 64-bit system, the largest an integer can be is 9223372036854775807 (just over 9 quintillion).
If an integer is too large, it's handled as a float. You can read the manual on integers for more information.
EDIT: The only way you're going to be able to "work" with the number in its entirety is to do so as a string.
$string = '[{"id":"130988929901015042","b":2,"c":3,"d":4,"e":5}]'; //Notice the additional double quotes around the number