Google paid $5.5 billion for Motorola's patent portfolio alone, according to a document filed Tuesday with the Securities and Exchange Commission. The rest of the money, some $7 billion, accounted for items like the company's cash on hand ($2.9 billion) and sheer "goodwill" ($2.6 billion).

Google announced its intention to buy Motorola back in August 2011. At the time, Larry Page, CEO of Google, stated that "Motorola has a strong patent portfolio, which will help protect Android." The OS was suffering many sidelong attacks from Apple by way of its hardware partners like Samsung and HTC (which returned fire with their own suits). Google received clearance for the deal in February 2012 from the US and Europe, and closed on the acquisition in May.

Of the $12.4 billion Google ultimately paid for Motorola, $730 million was paid for "customer relationships" and $670 million for "other net assets acquired" to round out the purchase price. "The goodwill of $2.6 billion is primarily attributed to the synergies expected to arise after the acquisition," reads the SEC document. Google continues to maintain that it will operate Motorola as an independent entity, rather than absorbing it as a hardware arm of Google itself.