And we are confident that the strategic plan as outlined will deliver a directional earnings range between $3 and $3.50 per share by 2024.
We ended the year with a backlog of $25.6 billion and full year new awards of $9 billion.
Approximately 35% of our infrastructure revenue will come from zero-margin work in 2021.
With respect to our two challenged government projects, I'm pleased to report that on the Radford project, we have turned overall 113 systems to our clients, and we are essentially complete.
As David said, Radford is essentially complete with all 113 systems turned over to BAE, while Warren will flow through at zero margin until its completion.
For 2020, Fluor reported a net loss from continuing operations attributable to Fluor of $294 million or a loss of $2.09 per diluted share.
During the year, we recognized the following significant charges, most of which were recorded in quarter one: $298 million for impairments of goodwill and tangible assets, investments and other assets; $60 million for current expected credit losses associated with Energy & Chemicals clients; $146 million for impairments of assets held for sale included in discontinued operations, of which $12 million related to goodwill; as well as significant forecast revisions for project positions due to COVID-19-related schedule delay and associated cost growth.
Corporate G&A expenses for 2020 was $241 million, up from $166 million a year ago.
For the full year, $47 million was due to foreign exchange currency losses predominantly driven by the weakening of the U.S. dollar, and $42 million was attributable to the professional fees associated with the 2020 internal review.
We achieved an estimated run rate savings of $140 million annually in our overhead expenses due to actions taken in 2020.
As I mentioned last month, we expect to achieve an additional $100 million of annual savings over the next three years as we rationalize overhead to the new shape of our business.
During the fourth quarter, we exited two of our European infrastructure P3 investments and received cash of approximately $20 million.
Our ending cash balance was $2.2 billion, up from 2019.
Domestic available cash represented 32% of this total.
We expect to see our cash holding steady around $2 billion through the year, with debt retirement being offset by divestitures and the liquidity improvement measures we have discussed in the past.
Operating cash flow for the full year was $186 million, which included approximately $375 million of cash to fund our legacy projects.
Additionally, our debt-to-capitalization requirement on this amendment facility was expanded to 0.65 times, which gives us more flexibility in current borrowing capacity as we assess our capital needs moving forward.
We are introducing our 2021 adjusted earnings per share guidance of $0.50 to $0.80 per diluted share for continuing operations.
Our assumptions for 2021 include: a slight decline in revenue as compared to 2020, adjusted G&A expense of approximately $40 million to $50 million per quarter and a tax rate of approximately 28%.
We anticipate average full year margins of 2% to 3% in Urban Solutions, 2.5% to 3% in Mission Solutions and margins of 2.5% to 3.5% in Energy Solutions and improving as the year progresses.
We also anticipate 2021 capital expenditures to be below $100 million as we divest our AMECO business this year.
As David reaffirmed, we maintain our long-term guidance of $3 to $3.50 of earnings per share by 2024.

Summary:
We ended the year with a backlog of $25.6 billion and full year new awards of $9 billion.
We are introducing our 2021 adjusted earnings per share guidance of $0.50 to $0.80 per diluted share for continuing operations.