But the initial successes of detachables by all vendors were not enough to make up for the precipitous decline in tablets. All types of tablets declined 10% in 2015, with pure slate standalone tablets declining by 21%, according to market research firm IDC.
IDC reported Monday that Apple's iPad Pro was the top-selling detachable for the fourth quarter of 2015 with about 2 million sold. Apple was the clear winner even though the company saw an overall decline of 25% in tablet shipments for the quarter compared to the same period a year ago.
Detachables, however, finished with an all-time high of 8 million devices shipped in the fourth quarter, more than doubling their total over the fourth quarter of 2014, which reached 3.1 million, IDC analyst Jitesh Ubrani said in an interview.
Samsung finished second in the quarter with an 18% decline. But Amazon surged into third place, with a $50 slate standalone tablet that was the holiday season's "surprise hit," according to IDC. That tablet, the latest Fire model, comes with a 7-in. display, Wi-Fi and 8GB of storage. It sells for $49.99 with free shipping on Amazon.
Detachables are growing fast because end users see them as laptop replacements, IDC analyst Jean Philippe Bouchard said in a statement. He said Apple sold more than 2 million iPad Pros, while Microsoft sold about 1.6 million Surface devices, of which most were the Surface Pro and not the more affordable Surface 3.
"It's clear that price is not the most important feature considered, when buying a detachable — performance is," Bouchard said.
After Apple, Samsung and Amazon in the top three positions for the fourth quarter in tablet shipments, Lenovo finished fourth and Huawei was fifth. There were 66 million tablets of all types shipped in the quarter, down nearly 14% from the fourth quarter of 2014.
For all of 2015, Apple and Samsung were first and second, while Lenovo, Asus and Huawei finished out the next three spots. For the entire year, all types of tablets shipped reached nearly 207 million, IDC said, down 10% from the 230 million shipped in 2014.
IDC said the transition to detachables has been positive for Apple and Microsoft but "lackluster" for Android tablets. Ubrani said Android "will require a lot more refinement to achieve any measurable success."
Android tablets need to add multi-window capability to be able to support multiple apps running simultaneously on a single screen, Ubrani added. It's possible that multi-window capability will come in the next generation of Android, the "N" version, sometime later this year.
In addition, Ubrani said Android tablets need to support more of their own tablet-oriented apps, and not primarily smartphone-oriented apps.
IDC's definition of the detachable category includes those devices that vendors term 2-in-1s where the tablet portion can be separated from the keyboard/cover portion. Vendors also include under the heading of 2-in-1s those so-called convertible laptops like the Yoga from Lenovo, which has a hinged, clamshell design where the display can be swiveled and folded down on the keyboard, but cannot be detached. The Yoga and other convertibles are counted as laptops by IDC and not as tablets, Ubrani said.
Ubrani said "Apple did a great job so far" with the iPad Pro, even though some reviewers gave it lukewarm reviews because of its high price. The basic model of the iPad Pro with 32 GB and Wi-Fi-only starts at $799, and Apple charges $169 extra for the Smart Keyboard to give it more laptop-like functionality.