Well, in the last 24 hours the retention has gone down from 15k to 500quid as the bits of paperwork have mysteriously appeared. Should be getting the keys "in the next hour or so". We'll see about that.
It's not an idiom, it's correct. 'Turning' is perfectly OK as a gerund. 'ing' appears in three places in Engish - as a gerund, as a progressive tense - both of which involve adding 'ing' to a verb, and as a noun-forming modifier for which I cannot find the correct terminology. The latter case involves adding 'ling' to a non-verb to produce a commonly-diminutive noun. Examples include underling, sapling, darling, sidling (which produced the verb sidle as a back formation). It used to be side-ling - i.e. someone who stands at your side as opposed to a subordinate under-ling. But of course given a variety of words ending in 'ing' it isn't always apparent that some were fromed from the 'ling'-route rather than the verbal 'ing'-route. The 'l' is a useful indicator, but not 100% reliable.