Share-based Compensation - Summary of Stock Options and Share Rights and Changes (Detail)		12 Months Ended
Dec. 31, 2012	Dec. 31, 2012 Pre-IPO Plans [Member] EUR (€)	Dec. 31, 2011 Pre-IPO Plans [Member] EUR (€)	Dec. 31, 2012 Post-IPO Plan [Member] USD ($)	Dec. 31, 2011 Post-IPO Plan [Member] USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options, Outstanding at January 1	15,114,216	16,128,196	18,050,123	7,366,908	3,749,932
Stock options, Granted				4,972,081	4,045,537
Stock options, Exercised		(544,462)	(1,051,993)	(637,858)	(71,542)
Stock options, Forfeited		(469,518)	(869,934)	(791,017)	(357,019)
Stock options, Outstanding at December 31	15,114,216	15,114,216	16,128,196	10,910,114	7,366,908
Stock options, Exercisable at December 31		2,372,254	2,875,053	1,819,243	853,732
Weighted average exercise price, Outstanding, beginning balance		€ 24.46	€ 23.30	$ 15.49	$ 13.27
Weighted average exercise price, Granted				$ 23.36	$ 17.35
Weighted average exercise price, Exercised		€ 7.65	€ 6.61	$ 14.14	$ 13.27
Weighted average exercise price, Forfeited		€ 21.86	€ 22.08	$ 15.94	$ 13.65
Weighted average exercise price, Outstanding, ending balance		€ 25.14	€ 24.46	$ 19.12	$ 15.49
Weighted average exercise price, Exercisable, ending balance		€ 11.96	€ 12.46	$ 15.05	$ 13.27

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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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 vested portions of options outstanding and currently exercisable under the stock option plan.

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Gross number of share options (or share units) granted during the 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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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated.

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Weighted average price at which grantees can acquire the shares reserved for issuance on stock options awarded.

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Number of shares (or other type of equity) forfeited during the period.

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

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