Over the course of its 20-year history, Fortune’s Best Companies to Work For list has featured a total of 452 different employers as firms have found their way on the list, then off, and sometimes back on again. But 12 companies have remained constant, meaning they have made the list every year for 20 straight years. We’ll call them “the Legends.” Who are they? Cisco, REI, Wegmans, TDIndustries, Publix, Marriott, SAS Institute, W.L. Gore & Associates, Whole Foods, Goldman Sachs, Four Seasons, and Nordstrom.
The group is a study in variety, from financial giants to a family-owned grocer, but they each possess some of the hallmarks of a Best Company: Goldman and REI offer fully paid sabbaticals; SAS, Marriott, Cisco, and Publix offer on-site childcare; six of the 12 give employees paid time off to volunteer. Eight of the 12 allow for job sharing, 11 offer compressed workweeks, and 10 provide college-tuition reimbursement.
But there’s one thread that runs across all dozen companies: Their generous treatment of employees is not reserved for full-time staffers. Many aspects of it extend to part-time workers too.
For some of the Legend companies, part-timers are a tiny portion of their overall workforce. But seven of the 12 are either a retailer or a hotel, meaning they employ sizable part-time workforces in labor-intensive service industries. Whole Foods, for instance, reports a part-time staff (as of 2016) of almost 27,000. Nordstrom has almost 30,000; at Publix there are more than 100,000.
All the Legend companies offer their part-time workers health insurance, a benefit that just 19% of the U.S.’s private part-time workforce receives, according to government figures. The Affordable Care Act (ACA) requires that all employers with 50 or more workers offer health care coverage to employees who average at least 30 hours a week. Some of the Legend companies abide by that 30-hour threshold, but others require far fewer. At Whole Foods, workers can get company-sponsored health insurance with just 20 hours a week.
Paid time off is another benefit that some Legend companies dole out to part-timers, and it’s also scarce in the larger labor force, with just 30%, 36%, and 40% of overall part-timers having access to paid sick days, vacation time, and holidays, respectively. But at Nordstrom, all part-time workers receive 19 paid days off. At Marriott, they get 18; at REI, 16.
There are other, less quantifiable perks for part-timers too. At Publix, part-time workers are eligible for employee stock-ownership plans that provide retirement savings at no cost to the individual. At Four Seasons, part-time employees receive free stays at the company’s hotels.
At Wegmans, many part-time workers end up building careers with the company, so the 100-year-old supermarket chain thinks of them no differently than full-time staff, says Becky Lyons, director of health and wellness. Last year, more than 50% of the 23,500 positions Wegmans hired for were filled by internal candidates, and of its 92 store managers, a majority started working for Wegmans as teenagers. The store covers 85% of health care premiums for part-timers, gives them six paid days off annually, and makes them eligible for a scholarship program that paid out $5 million in tuition in the current academic year. Those benefits serve as tools to retain these workers, allowing the company to pull from an experienced talent pool to fill full-time positions, Lyons says. The turnover among Wegmans’ part-time staff is 25%, about half the average for the food retail industry.
Wegmans hits on a reason the trend of offering benefits to part-time workers seems to be growing, even outside this rarefied group. Some companies that recently expanded their parental-leave policies—Hilton, No. 26 on the Best Companies list, and Ikea, No. 72—made the benefit available to all employees, no matter their employment status. Employers are learning that these perks are ultimately cost savers, since they build loyalty among workers, which reduces turnover expenses, says Teresa Boyer, a professor at Rutgers School of Management and Labor Relations. She says companies’ growing reliance on big data has shown them how expensive “churn” can be, even among part-time employees.
The ACA is a factor too, says Beth Livingston, a professor of human resources studies at Cornell University. Because it requires companies to provide health insurance to some hourly workers, it “pushed the conversation of what a part-time worker is and what they deserve.”
A version of this article appears in the March 15, 2017 issue of Fortune with the headline “Legends List.”