The vast majority of Apple’s revenue still comes from iPhones, Macs, iPads and other hardware. But its Services business has become its fastest-growing segment — and hidden within that unit is a content business that’s growing tremendously.

A little more than 80% of Apple’s total revenues over the past year have come from hardware sales, with iPhones accounting for nearly two-thirds of the total and iPads and Macs another 20%. But Apple’s Services segment generated around 13% of the total.

The segment includes iTunes, iBooks and the App Store as well as revenues from Apple Music, Apple Pay and money Google sends to Apple for featuring its search engine in its Safari browser. It’s become the fastest-growing part of Apple’s business, averaging 20% growth year on year even as Apple’s iPhone business has shrunk a little.

source: Company Reporting, jackdaw research Analysis and estimates *excluding Parks & Resorts

The Services business has become so important to Apple that the company has set a formal target of doubling revenues from the segment between 2016 and 2020. But the segment is also something of a black box, containing many different parts of Apple’s business across a range of areas, none of which Apple breaks out explicitly.

Yet it’s possible to arrive at some pretty decent estimates of the size of the constituent parts and, specifically, to break out the content business. That business generated about $15 billion in net revenue for Apple in 2016 — around 7% of its total revenues.

If we look at Apple’s gross take from its content business, the number is even more impressive. On that basis, revenue was nearly $8 billion in the March 2017 quarter, and the scale of the content business is approaching that of some of the largest congloms.

source: Company Reporting, jackdaw research Analysis and estimates

That quarterly revenue number was roughly double CBS’ quarterly income; it was about the size of total 21st Century Fox revenues toward the end of last year; and it eclipsed NBCUniversal business (minus theme parks). The only major content businesses bigger were Time Warner’s and Disney’s. And Apple is rapidly closing in on Time Warner.

This scale and rapid rate of growth make Apple’s content business unique among its peers, and that puts it in a powerful position to invest, even in original content. We’re seeing the start of that effort with a series of acquisitions for videos to play in Apple Music, including a series from “The Late Late Show” host James Corden. But Apple could easily increase that spending if it becomes serious about a stand-alone subscription video offering. So far, the company isn’t trying to compete directly with Netflix, which it sees as a partner and a customer. But there’s no financial reason why Apple couldn’t begin to challenge not just Netflix but Amazon, HBO, Hulu and any number of other players that invest in original content.

Jan Dawson is the founder and chief analyst at Jackdaw Research, an advisory firm for the consumer technology market.