The Fox Business debate briefly threatened to heat up when Neil Cavuto asked Ben Carson whether the media attacks on his past record were hurting his campaign.

But Carson responded coolly by saying he has no problem being vetted, he has a problem “with being lied about”—and pivoted to calling Hillary Clinton a liar on Benghazi.

Things flared again when Donald Trump talked about building a wall to stop lawbreaking Mexican immigrants and John Kasich called Trump’s plan to initially deport 11 million illegal immigrants “silly.” Trump hit back, and Jeb Bush agreed with Kasich, saying that Hillary’s campaign is “doing high fives” over the debate.

But the moderators here in Milwaukee kept steering the discussion back to economic growth, jobs, wages, taxes, entitlement reform—the high-road approach they had promised.

My take: Trump and Carson did nothing to hurt themselves or jeopardize their leads. Marco Rubio and Ted Cruz were solid as well. Jeb Bush had his best debate, but didn’t break through with any memorable lines.

The debate began on a serious note and pretty much stayed there.

Trump and Carson opposed any hike in the minimum wage. So did Marco Rubio, who reminded viewers that his dad was a bartender and his mother a maid. Kasich, not to be outdone, said his father was a mailman and his grandfather a coal miner.

By the time Maria Bartiromo asked Cruz about the International Monetary Fund, it was clear here in Milwaukee that substance would be the evening’s theme.

Even Bush got off to a forceful start, ripping President Obama’s regulations and citing the Wall Street Journal’s praise for his tax plan, but said nothing about his famous parents.

Carly Fiorina also personalized her first answer, talking about a woman she met who goes to bed afraid for her children’s future.

After CNBC’s Colorado calamity, the spotlight shifted to the Fox Business moderators—Neil Cavuto and Bartiromo, joined by Wall Street Journal editor Gerard Baker—and whether they would arouse the ire of candidates who were scoring points by bashing the media. But there were no sharply personal questions or attempts to get the candidates to denounce each other by citing incendiary quotes.

About the only attack on the media came when Cruz accused them of not understanding the illegal immigration issue. What if “a bunch of people with journalism degrees,” he asked, were coming across the border and driving down press wages?

Cavuto asked the cheekiest question when he noted that Carson’s flat-tax plan—a levy of 15 percent—was, unlike Trump’s, based on tithing: “Whose plan would God endorse?” Carson said he was just borrowing the biblical concept.

From there, the moderators and the candidates went deep into the weeds of tax policy, and the blizzard of numbers was sometimes hard to follow there was a drilldown on trade policy, driven by Baker.

Rubio called Rand Paul an isolationist, and Paul said Rubio would boost military spending so much that he wasn’t really a conservative. Trump complained about Fiorina interrupting. But that was about it for hard jabs.

The 90-second answers allotted candidates added weight and context to the candidates’ answers, but allowed less time for followup questions. That was the tradeoff.

Still, the moderators picked their spots, such as when Cruz riffed on his tax plan and Bartiromo asked how he would pay for it.

Some viewers may have been bored by all the policy talk. But this was what people claim they want: candidates arguing about substance.

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Howard Kurtz is a Fox News analyst and the host of "MediaBuzz" (Sundays 11 a.m. and 5 p.m. ET). He is the author of five books and is based in Washington. Follow him at @HowardKurtz. Click here for more information on Howard Kurtz.