Find the SD card using diskutil list:

todd:~ todd$ diskutil list
/dev/disk0
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *251.0 GB   disk0
   1:                        EFI EFI                     209.7 MB   disk0s1
   2:          Apple_CoreStorage                         250.1 GB   disk0s2
   3:                 Apple_Boot Recovery HD             650.1 MB   disk0s3
/dev/disk1
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                  Apple_HFS Macintosh HD           *249.8 GB   disk1
                                 Logical Volume on disk0s2
                                 5931BF6D-C779-4723-94C6-5831AF22BC00
                                 Unlocked Encrypted
/dev/disk2
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:     Apple_partition_scheme                        *17.5 MB    disk2
   1:        Apple_partition_map                         32.3 KB    disk2s1
   2:                  Apple_HFS Flash Player            17.4 MB    disk2s2
/dev/disk3
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:     FDisk_partition_scheme                        *15.9 GB    disk3
   1:             Windows_FAT_32 boot                    62.9 MB    disk3s1
   2:                      Linux                         15.9 GB    disk3s2

Unmount the SD card:

todd:~ todd$ diskutil unmountDisk /dev/disk3
Unmount of all volumes on disk3 was successful

Copy the image to the SD card using dd and use pv to display progress:

todd:~ todd$ pv ~/Downloads/2015-11-21-raspbian-jessie.img | sudo dd bs=16m of=/dev/disk3
837MiB 0:05:19 [3.21MiB/s] [=======>                              ] 22% ETA 0:18:29