In the treacherous world of finance, where investors confront biased advice, hidden costs and onerous fees, one investment giant seems to stand apart — the Teachers Insurance and Annuity Association, also known as TIAA. Calling itself a “mission-based organization” with a “nonprofit heritage,” TIAA has enjoyed a reputation as a selfless steward of its clients’ assets for almost a century. “Our values make us a different kind of financial services organization, known for our integrity,” Roger W. Ferguson Jr., TIAA’s president and chief executive, says on the company’s website.