When converted spot colors to cmyk the breakdown is different in CS6
In CS3, Cs4, Cs5, CS5.5 and my pantone spot color book converted to cmyk all match.
In CS6 Pantone solid ink libraries are all defined as Lab colors so the conversion to CMYK varies depending on your document's CMYK profile and Color Setting's conversion options. If you want Pantone's recommended CMYK solid ink simulation use Pantone+ Color Bridge.
Pantone+ Color Bridge was closer, however still not exact as other versions
PMS 187 Inside my Pantone book c-0 m-100 y-79 k-20
PMS 187 inside CS6 c-22.3 m- 100 y- 88.93 k- 14.68
PMS 187 Color bridge CS6 c-7 m-84 y- 56 K - 16
Inside CS 5.5 and all others.... PMS 187 c-0 m-100 y- 79 k-20
EXACT MATCH In older versions
PMS 187 Inside my Pantone Book c-0 m-100 y-79 k-20
If you want the older Pantone CMYK simulations, copy the PANTONE solid to process.acb file from and older version of ID and put it in your Presets>Swatch Libraries folder and use that library.
PMS 187 Color Bridge CS6 c-7 m-84 y-56 k-16
Looks like you are in Color Bridge Uncoated—the coated simulation is 7|100|82|26
PMS 187 Inside CS6 c-22.3 m-100 y-88.93 k-14.68
This is a color managed conversion from the solid Lab values to CMYK and is dependant on your document's CMYK profile. If you change your document's CMYK profile you will get a different conversion.