Fair Value Measurement (Unaudited) (Details) (USD $) In Millions	Jun. 30, 2011
Fair Value, Measurements, Recurring [Member] | Money market funds [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Cash equivalents:
Cash equivalents	$ 4,112
Trust assets (current and long-term):
Trust assets	12
Available-for-sale securities:
Available-for-sale securities	3
Fair Value, Measurements, Recurring [Member] | Money market funds [Member] | Fair Value, Inputs, Level 1 [Member]
Cash equivalents:
Cash equivalents	4,112
Trust assets (current and long-term):
Trust assets	12
Available-for-sale securities:
Available-for-sale securities	3
Fair Value, Measurements, Recurring [Member] | Money market funds [Member] | Fair Value, Inputs, Level 2 [Member]
Cash equivalents:
Cash equivalents	0
Trust assets (current and long-term):
Trust assets	0
Available-for-sale securities:
Available-for-sale securities	0
Fair Value, Measurements, Recurring [Member] | Money market funds [Member] | Fair Value, Inputs, Level 3 [Member]
Cash equivalents:
Cash equivalents	0
Trust assets (current and long-term):
Trust assets	0
Available-for-sale securities:
Available-for-sale securities	0
Fair Value, Measurements, Recurring [Member] | Time deposits [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Cash equivalents:
Cash equivalents	190
Available-for-sale securities:
Available-for-sale securities	15
Fair Value, Measurements, Recurring [Member] | Time deposits [Member] | Fair Value, Inputs, Level 1 [Member]
Cash equivalents:
Cash equivalents	190
Available-for-sale securities:
Available-for-sale securities	15
Fair Value, Measurements, Recurring [Member] | Time deposits [Member] | Fair Value, Inputs, Level 2 [Member]
Cash equivalents:
Cash equivalents	0
Available-for-sale securities:
Available-for-sale securities	0
Fair Value, Measurements, Recurring [Member] | Time deposits [Member] | Fair Value, Inputs, Level 3 [Member]
Cash equivalents:
Cash equivalents	0
Available-for-sale securities:
Available-for-sale securities	0
Fair Value, Measurements, Recurring [Member] | Cash Equivalents [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Cash equivalents:
Cash equivalents	4,302
Fair Value, Measurements, Recurring [Member] | Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member]
Cash equivalents:
Cash equivalents	4,302
Fair Value, Measurements, Recurring [Member] | Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member]
Cash equivalents:
Cash equivalents	0
Fair Value, Measurements, Recurring [Member] | Cash Equivalents [Member] | Fair Value, Inputs, Level 3 [Member]
Cash equivalents:
Cash equivalents	0
Fair Value, Measurements, Recurring [Member] | U.S. core fixed income funds [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Trust assets (current and long-term):
Trust assets	44
Fair Value, Measurements, Recurring [Member] | U.S. core fixed income funds [Member] | Fair Value, Inputs, Level 1 [Member]
Trust assets (current and long-term):
Trust assets	0
Fair Value, Measurements, Recurring [Member] | U.S. core fixed income funds [Member] | Fair Value, Inputs, Level 2 [Member]
Trust assets (current and long-term):
Trust assets	44
Fair Value, Measurements, Recurring [Member] | U.S. core fixed income funds [Member] | Fair Value, Inputs, Level 3 [Member]
Trust assets (current and long-term):
Trust assets	0
Fair Value, Measurements, Recurring [Member] | Government mortgage-backed securities [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Trust assets (current and long-term):
Trust assets	43
Fair Value, Measurements, Recurring [Member] | Government mortgage-backed securities [Member] | Fair Value, Inputs, Level 1 [Member]
Trust assets (current and long-term):
Trust assets	0
Fair Value, Measurements, Recurring [Member] | Government mortgage-backed securities [Member] | Fair Value, Inputs, Level 2 [Member]
Trust assets (current and long-term):
Trust assets	43
Fair Value, Measurements, Recurring [Member] | Government mortgage-backed securities [Member] | Fair Value, Inputs, Level 3 [Member]
Trust assets (current and long-term):
Trust assets	0
Fair Value, Measurements, Recurring [Member] | Corporate bonds [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Trust assets (current and long-term):
Trust assets	21
Fair Value, Measurements, Recurring [Member] | Corporate bonds [Member] | Fair Value, Inputs, Level 1 [Member]
Trust assets (current and long-term):
Trust assets	0
Fair Value, Measurements, Recurring [Member] | Corporate bonds [Member] | Fair Value, Inputs, Level 2 [Member]
Trust assets (current and long-term):
Trust assets	21
Fair Value, Measurements, Recurring [Member] | Corporate bonds [Member] | Fair Value, Inputs, Level 3 [Member]
Trust assets (current and long-term):
Trust assets	0
Fair Value, Measurements, Recurring [Member] | Asset-backed securities [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Trust assets (current and long-term):
Trust assets	18
Fair Value, Measurements, Recurring [Member] | Asset-backed securities [Member] | Fair Value, Inputs, Level 1 [Member]
Trust assets (current and long-term):
Trust assets	0
Fair Value, Measurements, Recurring [Member] | Asset-backed securities [Member] | Fair Value, Inputs, Level 2 [Member]
Trust assets (current and long-term):
Trust assets	18
Fair Value, Measurements, Recurring [Member] | Asset-backed securities [Member] | Fair Value, Inputs, Level 3 [Member]
Trust assets (current and long-term):
Trust assets	0
Fair Value, Measurements, Recurring [Member] | Government bonds and notes [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Trust assets (current and long-term):
Trust assets	11
Fair Value, Measurements, Recurring [Member] | Government bonds and notes [Member] | Fair Value, Inputs, Level 1 [Member]
Trust assets (current and long-term):
Trust assets	0
Fair Value, Measurements, Recurring [Member] | Government bonds and notes [Member] | Fair Value, Inputs, Level 2 [Member]
Trust assets (current and long-term):
Trust assets	11
Fair Value, Measurements, Recurring [Member] | Government bonds and notes [Member] | Fair Value, Inputs, Level 3 [Member]
Trust assets (current and long-term):
Trust assets	0
Fair Value, Measurements, Recurring [Member] | Municipal bonds [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Trust assets (current and long-term):
Trust assets	1
Fair Value, Measurements, Recurring [Member] | Municipal bonds [Member] | Fair Value, Inputs, Level 1 [Member]
Trust assets (current and long-term):
Trust assets	0
Fair Value, Measurements, Recurring [Member] | Municipal bonds [Member] | Fair Value, Inputs, Level 2 [Member]
Trust assets (current and long-term):
Trust assets	1
Fair Value, Measurements, Recurring [Member] | Municipal bonds [Member] | Fair Value, Inputs, Level 3 [Member]
Trust assets (current and long-term):
Trust assets	0
Fair Value, Measurements, Recurring [Member] | Equity securities [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Available-for-sale securities:
Available-for-sale securities	9
Fair Value, Measurements, Recurring [Member] | Equity securities [Member] | Fair Value, Inputs, Level 1 [Member]
Available-for-sale securities:
Available-for-sale securities	9
Fair Value, Measurements, Recurring [Member] | Equity securities [Member] | Fair Value, Inputs, Level 2 [Member]
Available-for-sale securities:
Available-for-sale securities	0
Fair Value, Measurements, Recurring [Member] | Equity securities [Member] | Fair Value, Inputs, Level 3 [Member]
Available-for-sale securities:
Available-for-sale securities	0
Fair Value, Measurements, Recurring [Member] | Embedded derivatives in provisional sales/purchases contracts [Member] | Fair Value, Inputs, Level 2 [Member]
Derivatives (Assets):
Derivative assets	0
Fair Value, Measurements, Recurring [Member] | Embedded derivatives in provisional sales/purchases contracts [Member] | Fair Value, Inputs, Level 3 [Member]
Derivatives (Assets):
Derivative assets	0
Fair Value, Measurements, Recurring [Member] | Copper futures and swap contracts [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Derivatives (Assets):
Derivative assets	10
Fair Value, Measurements, Recurring [Member] | Copper futures and swap contracts [Member] | Fair Value, Inputs, Level 1 [Member]
Derivatives (Assets):
Derivative assets	10
Fair Value, Measurements, Recurring [Member] | Copper futures and swap contracts [Member] | Fair Value, Inputs, Level 2 [Member]
Derivatives (Assets):
Derivative assets	0
Fair Value, Measurements, Recurring [Member] | Copper futures and swap contracts [Member] | Fair Value, Inputs, Level 3 [Member]
Derivatives (Assets):
Derivative assets	0
Fair Value, Measurements, Recurring [Member] | Atlantic Copper's copper forward contracts [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Derivatives (Liabilities):
Derivative liabilities	(9)
Fair Value, Measurements, Recurring [Member] | Atlantic Copper's copper forward contracts [Member] | Fair Value, Inputs, Level 1 [Member]
Derivatives (Liabilities):
Derivative liabilities	(9)
Fair Value, Measurements, Recurring [Member] | Atlantic Copper's copper forward contracts [Member] | Fair Value, Inputs, Level 2 [Member]
Derivatives (Liabilities):
Derivative liabilities	0
Fair Value, Measurements, Recurring [Member] | Atlantic Copper's copper forward contracts [Member] | Fair Value, Inputs, Level 3 [Member]
Derivatives (Liabilities):
Derivative liabilities	0
Fair Value, Measurements, Recurring [Member] | Embedded derivatives in provisional sales/purchases contracts [Member] | Fair Value, Inputs, Level 2 [Member]
Derivatives (Liabilities):
Derivative liabilities	0
Fair Value, Measurements, Recurring [Member] | Embedded derivatives in provisional sales/purchases contracts [Member] | Fair Value, Inputs, Level 3 [Member]
Derivatives (Liabilities):
Derivative liabilities	0
Fair Value, Measurements, Recurring [Member] | FMC's Copper Futures and Swap Contracts [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Derivatives (Liabilities):
Derivative liabilities	(2)
Fair Value, Measurements, Recurring [Member] | FMC's Copper Futures and Swap Contracts [Member] | Fair Value, Inputs, Level 1 [Member]
Derivatives (Liabilities):
Derivative liabilities	(2)
Fair Value, Measurements, Recurring [Member] | FMC's Copper Futures and Swap Contracts [Member] | Fair Value, Inputs, Level 2 [Member]
Derivatives (Liabilities):
Derivative liabilities	0
Fair Value, Measurements, Recurring [Member] | FMC's Copper Futures and Swap Contracts [Member] | Fair Value, Inputs, Level 3 [Member]
Derivatives (Liabilities):
Derivative liabilities	0
Fair Value, Measurements, Recurring [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Trust assets (current and long-term):
Trust assets	150
Available-for-sale securities:
Available-for-sale securities	27
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Trust assets (current and long-term):
Trust assets	12
Available-for-sale securities:
Available-for-sale securities	27
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Trust assets (current and long-term):
Trust assets	138
Available-for-sale securities:
Available-for-sale securities	0
Derivatives (Assets):
Derivative assets	0
Assets, Fair Value Disclosure	138
Derivatives (Liabilities):
Derivative liabilities	0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Trust assets (current and long-term):
Trust assets	0
Available-for-sale securities:
Available-for-sale securities	0
Derivatives (Assets):
Derivative assets	0
Assets, Fair Value Disclosure	0
Derivatives (Liabilities):
Derivative liabilities	0
Embedded derivatives in provisional sales/purchases contracts [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Derivatives (Assets):
Derivative assets	85
Embedded derivatives in provisional sales/purchases contracts [Member] | Fair Value, Inputs, Level 1 [Member]
Derivatives (Assets):
Derivative assets	85
Embedded derivatives in provisional sales/purchases contracts [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Derivatives (Liabilities):
Derivative liabilities	(43)
Embedded derivatives in provisional sales/purchases contracts [Member] | Fair Value, Inputs, Level 1 [Member]
Derivatives (Liabilities):
Derivative liabilities	(43)
Estimate of Fair Value, Fair Value Disclosure [Member]
Derivatives (Assets):
Derivative assets	95
Assets, Fair Value Disclosure	4,574
Derivatives (Liabilities):
Derivative liabilities	(54)
Fair Value, Inputs, Level 1 [Member]
Derivatives (Assets):
Derivative assets	95
Assets, Fair Value Disclosure	4,436
Derivatives (Liabilities):
Derivative liabilities	$ (54)