In a sign of the changing economics of the TV industry, as well as a boon for fans of quality television, FX has renewed "The Americans" for a third season of 13 episodes.

"The Americans," which stars Keri Russell and Matthew Rhys as KGB sleeper agents posing as an American couple in the early '80s, is one of the very best shows on television. Its live ratings, though, are modest, and have actually gone down a bit from last year's numbers. But the show also doubles its audience when you count those who watch via DVR or other methods within the first seven days of airing.

Every TV executive in the business has been trumpeting Live+7 numbers as a way to show that their audiences haven't slipped nearly as much as it seems from looking at overnight ratings. The question has been whether there's enough money to be made that way, given that advertisers aren't that interested in people who watch much later, especially if they'll be skipping commercials on their DVR'ed recording. But FX apparently has found a way to make the numbers work here.

When the second season premiered to disappointing numbers, FX's PR chief John Solberg said, "We fully expect 'The Americans' will be on our schedule for the next five years or more."

A new episode airs tonight at 10. It's a good one.