LIMITED POWER OF ATTORNEY

The undersigned hereby appoints each of
Brian J. Woram, Paul M. Johnston, Anita L. Nesser and James R. Peacock III
as his attorney-in-fact with full power to act in his name, place and stead
for the limited purpose of executing on his behalf all forms required to be
signed and filed by him under Section 16 of the Securities Exchange Act of
1934 and the rules and regulations promulgated thereunder.

IN WITNESS
WHEREOF, the undersigned hereunto sets his hand this 14th day of April
2005.


Juan L. Elek