Earnings Per Share (Tables)

12 Months Ended

Dec. 31, 2011

Earnings Per Share [Abstract]

Basic and diluted earnings per share

	Years ended December 31,
	2011			2010			2009
	(millions, except per share data)
Net income attributable to Willis Group Holdings	$	204		$	455		$	438
Basic average number of shares outstanding		173			170			168
Dilutive effect of potentially issuable shares		3			1			1
Diluted average number of shares outstanding		176			171			169
Basic earnings per share:
Continuing operations	$	1.17		$	2.68		$	2.58
Discontinued operations		0.01			—			0.03
Net income attributable to Willis Group Holdings shareholders	$	1.18		$	2.68		$	2.61
Dilutive effect of potentially issuable shares		(0.02	)		(0.02	)		(0.02	)
Diluted earnings per share:
Continuing operations	$	1.15		$	2.66		$	2.57
Discontinued operations		0.01			—			0.02
Net income attributable to Willis Group Holdings shareholders	$	1.16		$	2.66		$	2.59