Source: Plains All American corporate website

Plains All American Pipeline (NYSE: PAA) is a midstream energy company situated in the U.S. It differs from producers in that it operates energy infrastructure and provides logistics services rather than selling the underlying commodity. Its business is much less volatile than the typical producer. Despite its resiliency, fear in the markets and falling earnings caused the stock to decline 12% so far in 2015. At the current price of $45 per share, the company is yielding 6%. For a large cap company, this is no doubt an attractive proposition for many investors. However, we must be mindful of its future payouts, as sustainability is the key to good income investing.

History of Performance
Plains All American Pipeline has a good dividend history. It never skipped any payments and has been consistently increasing the dividend for well over a decade. Even during the middle of the financial crisis in 2008, dividend was paid and subsequently increased the following year. A company that can persist through a tough time when liquidity dried up is a company that you can trust.

PAA Dividend data by YCharts

Steady Throughout Commodity Cycles
Let's take a look at the income statement during the first quarter. While we don't want to focus on short term results, we should analyze whether large swings will impact the fundamentals. The first thing you notice is that total revenue fell by a whopping 49%. Despite this seemingly catastrophic decline, net income only decreased by 26%. This illustrates the aforementioned stability of the business. The company is able to achieve this because its costs are incredibly flexible. The quarter's operating margin of 6.2% actually increased compared to the first quarter of 2014, which was at 4.2%. This is evidence of the company's operating stability. In turn, you can expect consistent dividends.

A pretty income statement is nothing without the cash flow to back it up. For Plains All American Pipeline, this does not appear to be a problem. The operating cash flow has always been positive over the past couple of years. First quarter's operating cash flow did not deviate significantly from that of first quarter in 2014 ($732 million vs. $822 million). This further supports the aforementioned stability of the business. Even during a time when energy companies are struggling to stay afloat, the company is able to sustain its cash flow despite a massive slide in revenue.

Well Capitalized
Turning our attention to the balance sheet, there is no abnormally large payments due in the near future. Future debt payments are scheduled relatively smoothly, with an average payment of $936 million per year until 2019. Comparing this to the total immediately available liquidity of the company, which stands at $4.4 billion at the end of the first quarter, the company should have no problem meeting those obligations in the near future.

Short Term Setback?
On May 18, one of the company's pipeline ruptured in California, causing over 100 thousand gallons of oil to spill out, polluting the surrounding area. Total clean up costs were estimated to be $69 million. The company may also be fined by EPA for violations regarding the Clean Water Act. This isn't the first time management has had to deal with this type of situation. The company is no stranger to fines, it was fined as recently as 2010 for $3.25 million regarding a series of violations. Fortunately for you as a shareholder, these costs are a drop in the ocean when compared to the company's massive cash flow and deep liquidity.

A Foolish conclusion
As far as companies go, Plains All American is as stable as it gets. It is able to weather any commodity fluctuations that may cripple a less robust business; the company's cost flexibility allows it to shrink or expand rapidly according to the market environment; and its balance sheet is well managed with no evidence of stress. The company survived when oil was near $40 in 2008, with a much better macro environment today, there is little doubt that the company will be able to continually pay out to its shareholders.