requirements primarily with available cash and cash provided by operations, and long-term borrowings, and we also have availability under our unsecured Revolver. Our liquidity at June 30, 2022, is as follows (in thousands):
| | | | | | | | | |
| | | | | | | | | |
| | | Cash and equivalents | | $ | 1,007,085 | | | |
| | | Short-term investments | | | 351,005 | | | |
| | | Revolver availability | | | 1,182,885 | | | |
| | | Total liquidity | | $ | 2,540,975 | | | |
Our total outstanding debt of $3.0 billion decreased 2% during the first half of 2022 from reductions in revolver borrowings at one of our controlled subsidiaries. Our total long-term debt to capitalization ratio (representing our long-term debt, including current maturities, divided by the sum of our long-term debt, redeemable noncontrolling interests, and our total stockholders’ equity) was 28.8% and 32.9% at June 30, 2022, and December 31, 2021, respectively.
Our unsecured credit agreement has a senior unsecured revolving credit facility (Facility), which provides a $1.2 billion unsecured Revolver, and matures in December 2024. Subject to certain conditions, we have the opportunity to increase the Facility size by $500.0 million. The unsecured Revolver is available to fund working capital, capital expenditures, and other general corporate purposes. The Facility contains financial covenants and other covenants pertaining to our ability to incur indebtedness and permit liens on certain assets. Our ability to borrow funds within the terms of the unsecured Revolver is dependent upon our continued compliance with the financial and other covenants. At June 30, 2022, we had $1.2 billion of availability on the Revolver, $17.1 million of outstanding letters of credit and other obligations which reduce availability, and there were no borrowings outstanding.
The financial covenants under our Facility state that we must maintain an interest coverage ratio of not less than 2.50:1.00. Our interest coverage ratio is calculated by dividing our last-twelve-months (LTM) consolidated Adjusted EBITDA (earnings before interest, taxes, depreciation, amortization, and certain other non-cash transactions as allowed in the Facility) by our LTM gross interest expense, less amortization of financing fees. In addition, a debt to capitalization ratio of not more than 0.60:1.00 must be maintained. At June 30, 2022, our interest coverage ratio and debt to capitalization ratio were 61.01:1.00 and 0.29:1.00, respectively. We were, therefore, in compliance with these covenants at June 30, 2022, and we anticipate we will continue to be in compliance during the next twelve months.
Working Capital. We generated cash flow from operations of $1.8 billion in the first half of 2022 compared to $849.4 million in the same 2021 period. Operational working capital (representing amounts invested in trade receivables and inventories, less current liabilities other than income taxes payable and debt) increased $849.9 million, or 25%, to $4.2 billion at June 30, 2022, due primarily to increased accounts receivable, consistent with increased net sales, and funding of the $359.8 million in 2021 company-wide profit sharing in March 2022.
Capital Investments. During the first half of 2022, we invested $323.5 million in property, plant and equipment, primarily within our steel operations segment, compared with $587.1 million invested during the same period in 2021. Spending on Sinton decreased in the first half of 2022 versus the same period in 2021 as we completed the construction phase. We entered 2022 with ample liquidity of $2.4 billion and anticipated operating cash flow generation to provide for our planned 2022 capital requirements, including the four new flat roll coating lines at Sinton and Heartland. We announced on July 19, 2022, our plans to invest $2.2 billion in a new state-of-the-art low-carbon aluminum flat rolled mill with two supporting satellite recycled aluminum slab centers, which will be funded by available cash and cash flow from operations, beginning in 2022 through 2026.
Cash Dividends. As a reflection of continued confidence in our current and future cash flow generation ability and financial position, we increased our quarterly cash dividend by 31% to $0.34 per share in the first quarter of 2022 (from $0.26 per share in 2021), resulting in declared cash dividends of $126.4 million during the first half of 2022, compared to $108.3 million during the same period in 2021. We paid cash dividends of $115.0 million and $107.6 million during the first half of 2022 and 2021, respectively. Our board of directors, along with executive management, approves the payment of dividends on a quarterly basis. The determination to pay cash dividends in the future is at the discretion of our board of directors, after taking into account various factors, including our financial condition, results of operations, outstanding indebtedness, current and anticipated cash needs and growth plans.