These discussions will be followed by a Q&A period, and we expect the call to last about 60 minutes.
Revenue for the quarter was $1.569 billion.
Adjusted EBITDA was $166 million.
Adjusted earnings per share was $0.95.
Cash flow from operations was roughly $295 million, and year-to-date cash flow from operations was $497 million.
And backlog at quarter end was a second quarter record at $8.2 billion.
As one of the nation's leading clean energy construction companies, we have experienced significant growth over the last few years, growing revenues from $300 million in 2017 to over $1.5 billion of expected revenues this year.
Basically, if you don't have a lot of backlog today, the next 1.5 years will be tough.
First, in the midst of a pandemic, our revenue guidance for 2020 is only down about $200 million or 3% less than 2019 full year revenue.
Within that, our Oil and Gas revenue expectation is that it will be down approximately $800 million in 2020 from 2019.
That means the rest of our segment revenues will be up approximately $600 million versus last year in the middle of a challenging environment.
More importantly, margins on a year-over-year basis are expected to be relatively flat at 11.4% EBITDA margins versus 11.7% last year.
Our Communications revenue for the quarter was $654 million.
More importantly, margins came in strong, and we're up 370 basis points year-over-year and 380 basis points sequentially.
Revenue in our Electrical Transmission segment was $124 million versus $100 million in last year's second quarter.
Revenue was $426 million for the second quarter versus $250 million in the prior year, a 70% year-over-year increase.
We continue to achieve significant growth rates in this segment, and backlog at quarter end exceeded $1 billion.
Margins for this segment were strong at 7.1%, and we continue to expect margins to improve over 2019 by over 100 basis points.
Second quarter revenue was $369 million compared to revenues of $937 million in last year's second quarter.
We ended second quarter with backlog of almost $2.7 billion.
As a reminder, over the last three years, only 6% of our revenues have come from oil pipelines, with the majority of our business being tied to natural gas.
In summary, our second quarter 2020 results were better than expected, with adjusted EBITDA being the high end of our guidance expectation by $6 million, and adjusted diluted earnings per share exceeding the high end of our guidance expectation by $0.06.
These results also exceeded Street consensus, with adjusted EBITDA of $166 million beating Street consensus estimates by $14 million, and adjusted diluted earnings per share of $0.95 beating Street consensus by $0.15.
Second quarter 2020 results also continue our strong cash flow performance, generating $293 million in cash flow from operations and reducing sequential total debt levels by $177 million.
Our first half 2020 cash flow from operations of $497 million represents a record performance level for MasTec.
And we reduced total debt levels by $190 million during the first half of 2020 despite investing approximately $130 million in share repurchases and M&A.
This strong performance gives us confidence in our expectation that annual 2020 cash flow from operations will be at a new record level, approximating $600 million.
Subsequent to quarter end, we took advantage of favorable credit market conditions to refinance our four 7/8% $400 million senior unsecured notes, which we have called for redemption in mid-August.
Due to the strong demand for the new issue, our new senior unsecured notes offering was upsized by 50% to $600 million, with a lower interest rate of 4.5% and extended maturity to 2028 and overall better terms.
Second quarter 2020 Communications segment revenue of $654 million was basically flat with the same period last year.
Second quarter 2020 Communications segment adjusted EBITDA margin rate was 11.7% of revenue, representing a sequential increase of 380 basis points when compared to the first quarter of 2020 and a 370 basis point improvement when compared to last year's second quarter.
We are also increasing our annual 2020 Communications segment adjusted EBITDA margin rate expectation by approximately 100 basis points and now expect that Communications segment annual 2020 adjusted EBITDA margin rate will approximate 10% of revenue, which equates to a 200 basis point improvement over last year.
While we are pleased with the expected 200 basis point improvement in 2020 Communications segment adjusted EBITDA margin rate, especially in light of challenging conditions in 2020, it is important to note that this performance level still leaves ample room for future improvement in 2021 and beyond as pandemic conditions normalize and telecommunications market trends continue to develop.
As expected and previously communicated, second quarter 2020 Oil and Gas segment revenue of $369 million decreased 61% compared to the same period last year based on project start time.
Second quarter 2020 Oil and Gas segment adjusted EBITDA margin rate was 21.7% of revenue, continuing our strong performance trend with this performance, including the benefit of project mix comprised of reduced levels of lower-margin, cost-plus activity and continued strong project productivity on numerous smaller pipeline projects.
During the second quarter, we were awarded approximately $450 million in new Oil and Gas project awards, bringing the total of new backlog additions during the first half of 2020 to approximately $1.5 billion.
Second quarter 2020 Oil and Gas segment backlog of $2.66 billion represented a new all-time segment backlog record.
First half 2020 Oil and Gas segment award activity gives us strong visibility for solid project activity over the next 12 to 18 months.
Given the size of our large projects, a 30-day delay in project activity could impact monthly revenue by as much as $100 million to $150 million.
This results in annual 2020 Oil and Gas segment revenue now expected to approximate $2.3 billion, with solid backlog activity shifting into 2021.
Given that the majority of project activity shifting to 2021 is related to lower-margin, cost-plus activity, we are increasing our annual 2020 Oil and Gas segment adjusted EBITDA margin rate expectation from the high teens to the low 20% range.
Second quarter 2020 Electrical Transmission segment revenue increased approximately 24% compared to the same period last year to approximately $124 million, and segment adjusted EBITDA was a slight loss of approximately $3 million.
The project is approximately 90% complete as of the end of the second quarter, and we expect to recover a portion of these inefficiencies from our customer during the back half of 2020.
Our second quarter 2020 electrical distribution segment backlog of $551 million increased sequentially 27% or $117 million when compared to the first quarter, and this supports our continued belief that end-market conditions for this segment are supportive for strong 2021 revenue and adjusted EBITDA growth in this segment.
Second quarter 2020 Clean Energy and Infrastructure segment revenue of $426 million increased approximately 70% compared to the same period last year.
Second quarter 2020 adjusted EBITDA margin rate was 7.1% of revenue, a sequential increase of 540 basis points relative to the prior quarter and 360 basis points compared to the same period last year.
Now I will discuss a summary of our top 10 largest customers for the 2020 second quarter period as a percentage of revenue.
AT&T revenue, derived from wireless and wireline fiber services, was approximately 16% and install-to-the-home services was approximately 3%.
On a combined basis, these three separate service offerings totaled approximately 19% of our total revenue.
Permian Highway Pipeline was 10% of revenue.
Verizon, comprised of both wireline fiber and wireless services, was 6%.
Iberdrola, Comcast and Xcel Energy were each 5%.
And NextEra Energy, NG, Duke Energy and Enterprise Products were each at 4%.
Individual construction projects comprised 64% of our revenue, with master service agreements comprising 36%, once again highlighting that we have a substantial portion of our revenue derived on a recurring basis.
Lastly, it is worth noting, as we operate in a COVID-19-induced period of macroeconomic uncertainty, that all of our top 10 customers, which represented over 66% of our second quarter revenue, have investment-grade credit profiles.
During the second quarter, we generated $293 million in cash flow from operations and ended the quarter with net debt, defined as total debt less cash of $1.19 billion, which equates to a very comfortable book leverage ratio of 1.6 times.
We ended the quarter with DSOs at 90 days compared to 102 days last quarter.
During the first half of 2020, we generated a record-level $497 million in cash flow from operations, which allowed us to reduce our total debt levels by approximately $190 million, while investing in approximately $130 million in share repurchases and M&A.
During the first half of 2020, we repurchased approximately 3.6 million shares, or approximately 5% of our outstanding share base, with the vast majority of this activity occurring in the first quarter.
We currently have $158 million in open repurchase authorizations.
Based on our strong first half 2020 cash flow performance, we are increasing our expectation for annual 2020 cash flow from operations to approximate $600 million, a new record level.
As previously indicated, we opportunistically took advantage of market conditions after the end of the second quarter to further strengthen our capital structure through a successful offering of $600 million in new senior unsecured notes, maturing in 2028 with a favorable 4.5% coupon.
This offering is expected to close in early August and will allow us to redeem our existing $400 million four 7/8% senior notes at a lower interest rate, extend our maturity profile and will increase our overall liquidity by approximately $200 million, which should approximate $1.3 billion post closing.
Regarding capital spending, during the second quarter, we incurred net cash capex, defined as cash capex net of equipment disposals, of approximately $63 million, and we incurred an additional $80 million in equipment purchases under finance leases.
We currently anticipate incurring approximately $175 million in net cash capex in 2020, with an additional $115 million to $135 million to be incurred under finance leases.
Our third quarter 2020 revenue expectation is approximately $1.9 billion, with adjusted EBITDA guidance approximately $254 million or 13.4% of revenue and adjusted earnings per share guidance at $1.67.
We are projecting annual 2020 revenue to approximate $7 billion, with adjusted EBITDA expected to approximate $800 million or 11.4% of revenue and adjusted diluted earnings per share to approximate $4.93.
These guidance expectations incorporate the impact of projected lower second half 2020 Oil and Gas segment revenue as regulatory delays on two large projects are expected to lower 2020 project activity and shift awarded work into 2021, as well as improved 2020 EBITDA margin rate expectations in our Oil and Gas and Communications segments.
Based on our expected strong cash flow, lower nominal interest rates and our recent senior notes offering, we expect annual 2020 interest expense levels to approximate $63 million, with this level only including currently executed share repurchase activity.
Our estimate for full year 2020 share count is now 73.6 million shares.
It should be noted that, for valuation modeling purposes that based on the timing of repurchases, our year-end 2020 share count will approximate 73 million shares, and that's inclusive of the full impact of the repurchases made to date.
We expect annual 2020 depreciation expense to approximate 3.7% of revenue due to the combination of lower expected 2020 revenue levels and timing impact of capital additions and acquisition activity.
Lastly, we continue to expect that our annual 2020 adjusted income tax rate will approximate 24%.
This expectation includes our existing first half 2020 adjusted tax rate as well as the expectation that quarterly adjusted income tax rates for the balance of 2020 will approximate 26%, and this blend leads to an annual 2020 adjusted tax rate that approximates 24%.

Summary:
Our third quarter 2020 revenue expectation is approximately $1.9 billion, with adjusted EBITDA guidance approximately $254 million or 13.4% of revenue and adjusted earnings per share guidance at $1.67.
We are projecting annual 2020 revenue to approximate $7 billion, with adjusted EBITDA expected to approximate $800 million or 11.4% of revenue and adjusted diluted earnings per share to approximate $4.93.
These guidance expectations incorporate the impact of projected lower second half 2020 Oil and Gas segment revenue as regulatory delays on two large projects are expected to lower 2020 project activity and shift awarded work into 2021, as well as improved 2020 EBITDA margin rate expectations in our Oil and Gas and Communications segments.