The oil giant is a cash-generating (and returning) machine.Chevron's (CVX -2.67%) strategy of focusing on investing in its highest-return assets has paid big dividends over the years. The company is generating a growing stream of cash flow, which is giving it lots of money to return to shareholders. Over the last two years, it has sent its investors a whopping $50 billion via dividends and share repurchases. The oil company expects to produce even more cash in the future, which should enable it to continue ...