The Idle protocol is governed and upgraded by IDLE token-holders, using three distinct components: (1) the IDLE token, (2) the governance module (Governor Alpha), and (3) the Timelock.
Together, these contracts allow the community to propose, vote, and implement changes through the administrative functions of an idleToken or the IdleController. Proposals might include upgrades from adjusting the fee model to adding support for a new protocol.
Any address with at least 130,000 IDLE (1% of the total supply) delegated to it is able to propose governance actions, which are executable code. When a proposal is created, the community can submit their votes during a 3 day voting period. If a majority and at least 520,000 (4% of the total) votes are cast for the proposal, it is queued in the Timelock and can be implemented after 2 days.
Idle governance is based on the Compound governance architecture, for a more in-depth description of all methods available please refer to their guide here.
You can read more info on the role of governance in this article.