LIMITED POWER OF ATTORNEY


     KNOW ALL MEN BY THESE PRESENTS, that the undersigned individual,
V. Frank Pottow, does hereby appoint Katherine J. Ryan as his true and lawful
attorney to execute and deliver for him and in his name all Forms 3, 4 and 5
filed on behalf of the undersigned with the Securities and Exchange Commission.

     The undersigned hereby ratifies and confirms all that said attorney shall
do by virtue of the powers granted hereby.  The undersigned does hereby
indemnify such attorney, and holds such attorney harmless, from all claims which
may be made against the undersigned as a result of his serving as the
undersigned's attorney except to the extent that such claims result from his
willful misconduct.

     This Power of Attorney shall terminate immediately upon the undersigned's
written revocation hereof.

     IN WITNESS WHEREOF, and intending to be legally bound, the undersigned
has executed and delivered this Power of Attorney this 10th day of September,
2018.


                                            /s/ V. Frank Pottow
                                            ------------------------
                                            V. Frank Pottow