How to add transform in animator mecanim for character?

Hi All,

I have bought a model from asset store with animation of walking and idle. (which is common)
The animation is just "walking" and "idle" without transform of the character.

I want to do a NPC on the map to "randomly" walk around or repeat walking around.

So, I create a Animator Controller with two states:
Idle (repeat) <---------> Walk(repeat)
state transition by Exit time: 4 sec

However, how can I add transform of X + Z and the rotation when it turns back?

I try by adding an animation with loop by:
AnimationWrapper
---> Model with Animator Controller
And Animate the AnimationWrapper's transform.

But the timing seems not accurate between Animator and Animation I added.
The state transition time is not exactly 4 sec so my animation clip is difficult to match
with the animator.
What is the proper way to do such animation?

Thanks very very much in advance,
Billy