Noble Shaikh! The Qur’aaniyoon  say: Allaah says:
وَكُلَّ شَيْءٍ فَصَّلْنَاهُ تَفْصِيلًا
“And We have explained everything in detail with a full explanation.”
[Surah Al-Israa: 12]
And Allaah says:
مَّا فَرَّطْنَا فِي الْكِتَابِ مِن شَيْءٍ
“We have not neglected anything in the Book.”
[Surah Al-An’aam: 38]
And the Messenger of Allaah صلى الله عليه وسلم said: “Verily this Qur’aan – part of it is in the Hand of Allaah and part of it is in your hands. So hold fast onto it, for you will never go astray nor will you ever be ruined after it.” 
We would like your comments on this?
As for Allaah’s saying: “We have not neglected anything in the Book”, what is meant by the word “Book” here is the Preserved Tablet and not the Noble Qur’aan.
And as for Allaah’s statement: “And We have explained everything in detail with a full explanation”, if you attach what was explained previously to the Noble Qur’aan, then it becomes certain that Allaah has indeed explained everything in detail, however with another provision. You are aware that an explanation may at times be general, such as when one places general rules under which exist many particulars the likes of which cannot be confined due to their large number. So by the Wise Legislator placing well known rules for these many particulars, the meaning of the noble ayah becomes apparent.
The explanation may also be detailed, and this is what is obvious from this ayah as the Prophet صلى الله عليه وسلم said:
“I have not left behind anything that Allaah commanded me with except that I have ordered you to do it. And I have not left behind anything that Allaah forbade me from except that I have forbidden you from it.” 
So the explanation may at times be with rules, which many particulars (and details) fall under. And at other times it may be in such detail in terms of the vocabulary of the acts of worship and laws that it does not require being referenced to any of these rules.
Among the rules that numerous branches fall under – and which show the greatness of Islaam and the vast scope of Islaam in legislating – for example, are:
The Prophet’s صلى الله عليه وسلم statement: “There is no harming (of oneself) or others.” 
The Prophet’s صلى الله عليه وسلم statement: “Every intoxicant is alcohol and every alcohol is unlawful.” 
And his صلى الله عليه وسلم statement: “Every innovation is misguidance, and every misguidance is in the Hellfire.” 
These are rules and generalizations that do not exclude anything related to harming of one’s self or harming of one’s wealth, with respect to the first hadeeth, nor does it exclude anything related to that which intoxicates, with respect to the second hadeeth, whether the intoxicant is derived from grapes, which is the most popular form, or from corn or from any other substance. So long as the product is an intoxicant, it is unlawful (Haraam).
[Note: Read The Need for the Sunnah in order to Understand the Qur’aan – Shaykh al Albaani]
The same goes for the third hadeeth – it is not possible to take into account the number of innovations due to their large amount. It is not possible to account for all of them. However in spite of this, this hadeeth – even though brief in size – states with all clarity: “Every innovation is misguidance, and every misguidance is in the Hellfire.”
This is a detailed statement but with rules.
As for the laws that you are aware of, they are explained in detail by words that have been mentioned in the Sunnah in most cases and at times they are mentioned in the noble Qur’aan as is the case with the laws of inheritance, for example.
As for the hadeeth that was mentioned in the question, then it is an authentic hadeeth, and acting upon it is what we should try to adhere to as stated in the hadeeth in which the Prophet صلى الله عليه وسلم said: “I have left two things amongst you by which you will never go astray so long as you hold steadfast onto them: The Book of Allaah and the Sunnah of His Messenger.” 
So holding steadfast onto the Rope of Allaah – which is in our hands – refers to acting upon the Sunnah, which explains the noble Qur’aan.
 Translator’s Note: This is a name given to those who claim that the Qur’aan is sufficient for deriving rules and laws in Islaam and that there is no need to turn to the Sunnah. Some even go so far as to reject the Sunnah in its entirety and rely solely on the Qur’aan.
 Saheeh At-Targheeb wat-Tarheeb (1/93/35)
 Silsilat-ul-Ahaadeeth as-Saheehah (1803)
 Saheeh al-Jaami’-us-Sagheer (7517)
 Irwaa’-ul-Ghaleel (8/40/2373)
 Saheeh at-Targheeb wat-Tarheeb (1/92/34) and Salaat-ut-Taraaweeh (pg. 75)
 Mishkaat-ul-Masaabeeh (1/66/186)