Senate Majority Leader Harry M. Reid presented an $848 billion healthcare overhaul package that would extend coverage to 31 million Americans and reform insurance practices while adding an array of tax increases. The Senate measure is similar in scope to legislation the House approved earlier in November. It would require most people to buy insurance, and if their employers did not offer affordable coverage, they would be able to shop for policies on new state-based "exchanges" that would function as marketplaces for individual coverage. Insurance companies would have to abide by new rules that would ban practices such as denying coverage based on preexisting conditions.