How many miles do you ahve on it? Blue smoke would indicate burning oil but white smoke could be anything from condensation in muffler to catalytic converter issues. If you dont have any CEL lights on then its more than likely condensate. As the oxygen sensors in the exhaust system would have lit the CEL if it was malfunctioning. If you have a local autoparts store such as Autozone, Advanced Autoparts, Oreilly, etc. they have machines that can check engine and see if any problem codes are stored in engine computer. Otherwise if performance is ok this isnt a major problem
The same thing happened to my 2003 ES300 - the smoke is coming from the oil seeping into the motor's cylinders. This is the classic "Oil Gelling" problem in Toyota and Lexus vehicles. There is a factory recall on it, but it only covers to 2002 ES300 not 2003. The Lexus dealer confirmed my "oil gel" problem and went to bat for me with Lexus - they got the repair approved - Thank you Mr Local Lexus Dealer! The cost was nearly $4,000 - paid for by Lexus.