Ask HN: Can you protect an idea?

Ideas are a dime a dozen - right? Is it a meaningless endeavor to protect your startup idea? Let's just say it is amazing. Did the WhatsApp and Instagrams of the world protect their IP or just launch as quickly as possible to gain traction and validate themselves in the market?

I am working on something (aren't we all) but my business partner is strongly suggesting we file something to protect the intellectual property. It's not a physical product, it's just a way of doing things differently.

Thoughts?