Cold debris disks have the potential to answer many outstanding questions in wide-orbit planet formation and evolution. We characterized the infrared excess SEDs of 174 cold debris disks with Spitzer IRS and MIPS. We found a trend between the temperature of the disks and the stellar type of the stars they orbit. This argues against the importance of strictly temperature-dependent processes (e.g. ice lines) in setting the dimensions of cold debris disks. We also found no evidence that delayed stirring causes the trend. The trend may result from outward planet migration that traces the extent of the primordial protoplanetary disk, or from planet formation that halts at an orbital radius limited by the efficiency of core accretion. For the full details of this work, see Ballering et al. (2013).