Did Turing ever describe the test in detail?
Yes, basically a person C is allowed to interact with actors A and B of which one is a human and the other is a computer. C's task is to determine who of A and B is the computer.
One should remember that the turing test is not a test of the computer's ability to be intelligent, but rather the ability to mimic human behaviour. Although one might have mixed feelings about impersonating a teenage kid on IRC, it's only a matter of throwing more computing power to pass more stronger versions of the test.
One conclusion is that the Turing Test is not that useful for measuring intelligence. On the other hand, if a computer gets good enough with mimicking human behaviour, and if it is able to make good enough decisions, it's will become useful, even though it's not "intelligent".