The homebuilder is buying back $1 billion or so of its debt, just the latest piece of good news from this beneficiary of the housing market rally that has lifted the entire industry. Earnings are coming in higher than expected, and the company reported more closings on new home purchases and higher sales prices on those homes for the third quarter. The company clearly seems to have navigated the financial crisis and the real estate debacle that accompanied it, and the market has rewarded it with a 161 percent gain.