Shareholders' Equity (Details) (USD $)
In Millions
3 Months Ended9 Months Ended
Sep. 30, 2011
Sep. 30, 2010
Sep. 30, 2011
Sep. 30, 2010
Dec. 31, 2010
Shareholders' equity activity [Roll Forward]     
Balance at beginning of period  $ 10,387$ 8,757 
Transactions with shareholders  299111 
Treasury shares issued for acquisition of Boots & Coots, Inc.   105 
Shares repurchased   (114) 
Comprehensive income:     
Net income6855451,9371,235 
Other comprehensive income   4 
Total comprehensive income6855451,9371,239 
Payments of dividends to shareholders  (247)(245) 
Balance at end of period12,3769,85312,3769,853 
Summary of comprehensive income [Abstract]     
Net income6855451,9371,235 
Other comprehensive income (loss)   4 
Total comprehensive income6855451,9371,239 
Comprehensive income attributable to noncontrolling interest21   
Comprehensive income attributable to company683544   
Accumulated other comprehensive loss [Abstract]     
Defined benefit and other postretirement liability adjustments(175) (175) (175)
Cumulative translation adjustments(66) (66) (66)
Unrealized gains on investments1 1 1
Total accumulated other comprehensive loss(240) (240) (240)
Company shareholders' equity [Member]
     
Shareholders' equity activity [Roll Forward]     
Balance at beginning of period  10,3738,728 
Transactions with shareholders  299131 
Treasury shares issued for acquisition of Boots & Coots, Inc.   105 
Shares repurchased   (114) 
Comprehensive income:     
Net income  1,9331,230 
Other comprehensive income   5 
Total comprehensive income  1,9331,235 
Payments of dividends to shareholders  (247)(245) 
Balance at end of period12,3589,84012,3589,840 
Summary of comprehensive income [Abstract]     
Net income  1,9331,230 
Other comprehensive income (loss)   5 
Total comprehensive income  1,9331,235 
Noncontrolling interest in consolidated subsidiaries [Member]
     
Shareholders' equity activity [Roll Forward]     
Balance at beginning of period  1429 
Transactions with shareholders  0(20) 
Treasury shares issued for acquisition of Boots & Coots, Inc.   0 
Shares repurchased   0 
Comprehensive income:     
Net income  45 
Other comprehensive income   (1) 
Total comprehensive income  44 
Payments of dividends to shareholders  00 
Balance at end of period18131813 
Summary of comprehensive income [Abstract]     
Net income  45 
Other comprehensive income (loss)   (1) 
Total comprehensive income  $ 4$ 4