Dozens of business make up Berkshire Hathaway (NYSE:BRK-A)(NYSE:BRK-B). But one insurance operation, launched just last year, is already delivering remarkable growth, which could mean major things not just for Warren Buffett, but for all of Berkshire Hathaway's shareholders.

The big business that could
In June of 2013, we learned that Berkshire Hathaway Specialty Insurance (BHSI) had officially started its efforts in America. Launched by none other than oft-praised insurance executive Ajit Jain, BHSI is the commercial property casualty insurance group that focuses on excess and surplus lines insurance, which allows companies to design specific policies and coverage depending on the needs of their businesses. 

At the time, Buffett remarked:

It's offi­cial: We are moving into commercial insurance in a substantial way, and we are here to stay. With our proven underwriting discipline and financial strength, along with a stellar management team, Berkshire Hathaway Specialty Insurance is a welcome solution for customers seeking large-scale property and casualty capacity for the long term.

He went on to add in the letter to Berkshire Hathaway shareholders this year that, thanks to the confidence firms have in Berkshire Hathaway, "BHSI will be a major asset for Berkshire, one that will generate volume in the billions within a few years."

And it may take less than just "a few years" for it to get there.

The running start
Earlier this year, we learned Berkshire Hathaway, in total, saw its total excess and surplus insurance premiums written -- which includes a few of its other businesses -- jump by $150 million, or nearly 40% in 2013, to stand at $561 million. The overall industry only saw premiums increase by 7.6%, and industry leader AIG (NYSE:AIG) saw its premiums actually fall by 4.2%, to $4.8 billion.

Although AIG clearly has the lead in the size of its business, Berkshire Hathaway has more efficient operations as measured by its combined ratio -- which is the measurement of its losses plus its expenses divided by its revenue.

Source: SNL Financial.

But it didn't just end at impressive growth in 2013; in the spring, the president of BHSI, Peter Eastwood, also revealed it is "working hard at some expansion plans in Asia and in Europe as well," and although it is "a little bit further down the road," it will also move to Latin America.

Eastwood went on to add, "We can build business anywhere in the world that we think is appropriate for us to build in, which means generating acceptable profit for Berkshire Hathaway."

The key thing for investors to see
With nearly $500 billion of assets on its balance sheet, it's easy to think Berkshire's days of its growth are long behind it. After all, the growth of the float of its insurance businesses -- the difference between what they receive in premiums from customers versus what is paid on claims -- over the years, has been incredible. But now, a gain of $150 million doesn't exactly move the needle:

Source: Company Investor Relations.

But the growth at these underlying businesses that make up Berkshire Hathaway will be the long-term drivers for this company. Very few individual businesses will move the overall Berkshire business, but that's a good thing. Buffett has de-risked the company's operations to a point where Berkshire can essentially run on its own.

One day, Buffett won't be steering the Berkshire-ship, but shareholders can rest easy knowing that units like BHSI, BNSF, Berkshire Hatahway Energy are chugging along.