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The weighted average price at which option holders acquired shares when converting their stock options into shares under the plan during the reporting period.

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The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

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The weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated during the reporting period due to noncompliance with plan terms during the reporting period.

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Net number of share options (or share units) granted during the period.

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The weighted average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on stock options awarded under the plan during the reporting period.

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The addition or reduction in the number of reserved shares that could potentially be issued under the option plan attributable to reasons other than grants, exercises, forfeitures, and expirations during the reporting period.

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The weighted average price at which grantees could acquire or could have acquired the underlying shares with respect to any other type of change in shares reserved for issuance under the stock option plan during the reporting period.

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The number of shares reserved for issuance under stock option agreements awarded under the plan that validly exist and are outstanding as of the balance sheet date, including vested options.

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The weighted average price as of the beginning of the year at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Number of share options (or share units) exercised during the current period.

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Details of Performance Vesting Restricted Shares and Share Appreciation Rights Granted Under Share Plan (Detail)															6 Months Ended	12 Months Ended			6 Months Ended	12 Months Ended
	Dec. 31, 2011 Stock Appreciation Rights ZAR	Dec. 31, 2010 Stock Appreciation Rights ZAR	Jun. 30, 2010 Stock Appreciation Rights ZAR	Jun. 30, 2009 Stock Appreciation Rights ZAR	Dec. 31, 2011 2005 Share Plan South Africa Rand ZAR	Dec. 31, 2010 2005 Share Plan South Africa Rand ZAR	Jun. 30, 2010 2005 Share Plan South Africa Rand ZAR	Jun. 30, 2009 2005 Share Plan South Africa Rand ZAR	Jun. 30, 2008 2005 Share Plan South Africa Rand ZAR	Dec. 31, 2011 2005 Share Plan U.S. Dollar USD ($)	Dec. 31, 2010 2005 Share Plan U.S. Dollar USD ($)	Jun. 30, 2010 2005 Share Plan U.S. Dollar USD ($)	Jun. 30, 2009 2005 Share Plan U.S. Dollar USD ($)	Jun. 30, 2008 2005 Share Plan U.S. Dollar USD ($)	Dec. 31, 2010 2005 Share Plan Restricted Stock	Dec. 31, 2011 2005 Share Plan Restricted Stock	Jun. 30, 2010 2005 Share Plan Restricted Stock	Jun. 30, 2009 2005 Share Plan Restricted Stock	Dec. 31, 2010 2005 Share Plan Stock Appreciation Rights	Dec. 31, 2011 2005 Share Plan Stock Appreciation Rights	Jun. 30, 2010 2005 Share Plan Stock Appreciation Rights	Jun. 30, 2009 2005 Share Plan Stock Appreciation Rights	Dec. 31, 2011 2005 Share Plan Stock Appreciation Rights South Africa Rand ZAR	Dec. 31, 2011 2005 Share Plan Stock Appreciation Rights U.S. Dollar USD ($)
Number of Options
Beginning Balance															8,438,663	7,650,081	6,831,964	5,396,887	5,660,272	5,270,597	4,609,626	3,837,937
Granted during the period															381,115	3,165,342	3,177,552	2,616,171	307,070	1,638,484	1,564,217	1,311,271
Exercised and released															(355,779)	(2,559,552)	(341,309)	(73,954)	(13,329)	(1,247,317)
Forfeited															(753,918)	(886,759)	(619,793)	(880,240)	(683,416)	(631,621)	(513,571)	(539,582)
Conditions for vesting not met															(60,000)		(609,751)	(226,900)
Ending Balance															7,650,081	7,369,112	8,438,663	6,831,964	5,270,597	5,030,143	5,660,272	4,609,626
Average price
Granted during the period					119.17	103.66	90.84	108.90		$ 16.51	$ 14.52	$ 11.98	$ 12.09
Exercised and released					111.06	103.07				$ 15.38	$ 14.44
Forfeited					110.69	104.01	109.40	121.07		$ 15.33	$ 14.57	$ 14.43	$ 13.44
Conditions for vesting not met
Average price, at end of year	119.17	93.89	90.84	108.90	107.91	105.53	106.00	111.50	112.73	$ 13.27	$ 15.63	$ 14.00	$ 13.83	$ 14.09									107.91	$ 13.27