Infrared and terahertz photodetectors are used extensively for applications in defense, communications, medical imaging, component inspection, and thermal imaging. Such detectors are often based on exotic semiconductor materials operated at low temperatures, and new approaches are sought that could lead to uncooled detectors or improved ease of integration with CMOS technology. In this presentation, I will discuss our recent efforts at developing and understanding carbon nanotube infrared and terahertz detectors. The detectors are based on macroscopic, optically-thick films of aligned single-wall carbon nanotubes, and are actualized using asymmetric contact electrodes or in p-n junction format. Responsivities of several Volts/Watt are observed in these devices, with a broadband spectral response spanning the visible to the terahertz. A combination of experiment and theory is used to demonstrate the origin of the responsivity and to discuss the performance attributes of such devices.