Earnings Per Share (Tables)

6 Months Ended

Jun. 30, 2011

Earnings Per Share (Tables) [Abstract]

Basic and diluted earnings per share

	Three months ended					Six months ended
	June 30,					June 30,
	2011			2010		2011			2010
	(millions, except per share data)
Net income attributable to Willis Group Holdings	$	85		$	89	$	119		$	293
Basic weighted average number of shares outstanding		172			170		172			169
Dilutive effect of potentially issuable shares		4			1		3			2
Diluted weighted average number of shares outstanding		176			171		175			171
Basic earnings per share:
Net income attributable to Willis Group Holdings shareholders	$	0.49		$	0.52	$	0.69		$	1.73
Dilutive effect of potentially issuable shares		(0.01	)		—		(0.01	)		(0.02	)
Diluted earnings per share:
Net income attributable to Willis Group Holdings shareholders	$	0.48		$	0.52	$	0.68		$	1.71