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) $ ...