Thanks a lot for always being of assistance

[Ryan.]

Hello,

Is this phrase idiomatic in English?

"Thanks a lot for always being of assistance"

Thanks a lot.

 

[Rover_KE]

It's grammatical, but I wouldn't say it's idiomatic.

'Thanks a lot for always being there to help.'
'Thanks a lot for always being helpful.'
'Thanks a lot for always helping.'