Three months ended    Three months ended    June 30,  March 31, sequential June 30,  year-over-year 2024 2024 change 2023 change(In millions, except per share amounts, percentages and backlog)              Contract drilling revenues$861$763  $98$729  $132 Adjusted contract drilling revenues$861  $767$94  $748$113 Revenue efficiency (1)96.9% 92.9% 4.0% 97.2% (0.3)%Operating and maintenance expense$534$523  $11$484  $50 Net income (loss) attributable to controlling interest$(123) $ ...