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

IN WITNESS WHEREOF, the undersigned hereunto sets her hand this 16th day of
October 2006.


Catherine R. Smith