Detroit back to investment-grade credit rating

Driving the news: Moody's Investors Service upgraded the city's bond rating two notches to "Baa2" on Friday.

Context: The ratings depict the quality of a government's debt — or how likely the city is to be able to repay that debt without defaulting on it.

• A lower rating means buying the city's "junk" bonds is riskier for investors while a high rating means they're a safe bet.
• Some investors only look at investment-grade bonds, meaning the update opens the city's bonds to a bigger market.
• A larger potential pool of investors could lower interest rates on the city's bonds, meaning it would cost less for the city to borrow money.

What they're saying: "It was not easy every year when people show up at City Council meetings and argue for things that were really urgent needs in a lot of areas, places where we could have put money, but to have the discipline to say 'no,' we're not going to spend more than we have," Mayor Mike Duggan said in a press conference Monday announcing the news.

The bottom line: "The city's tax base has doubled in the past five years and continued growth will be fueled by ongoing development and recent appreciation of residential values," Moody's wrote in its credit opinion.

• However, the city still faces challenges, including high resident unemployment and poverty, and a regional labor force that is too concentrated in automotive manufacturing.