Goodwill and Other Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2015

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of changes in the net carrying amount of goodwill by operating segment

The changes in the net carrying amount of goodwill by reportable segment for the years ended December 31, 2015 and 2014, respectively, are as follows (in millions):

	Risk Solutions			HR Solutions			Total
Balance as of January 1, 2014	$	6,020		$	2,977		$	8,997
Goodwill related to current year acquisitions	287			5			292
Goodwill related to disposals	(14		)	—			(14		)
Goodwill related to prior year acquisitions	(8		)	—			(8		)
Transfer	(2		)	2			—
Foreign currency translation	(372		)	(35		)	(407		)
Balance as of December 31, 2014	$	5,911		$	2,949		$	8,860
Goodwill related to current year acquisitions	2			16			18
Goodwill related to disposals	(1		)	(76		)	(77		)
Goodwill related to prior year acquisitions	—			—			—
Transfer	—			—			—
Foreign currency translation	(319		)	(34		)	(353		)
Balance as of December 31, 2015	$	5,593		$	2,855		$	8,448

Schedule of other intangible assets by asset class

Other intangible assets by asset class are as follows (in millions):

	As of December 31
	2015						2014
	Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount		Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount
Intangible assets with indefinite lives:
Tradenames	$	1,019	$	—	$	1,019	$	1,019	$	—	$	1,019
Intangible assets with finite lives:
Customer related and contract based	2,886		1,809		1,077		2,952		1,579		1,373
Technology and other	541		457		84		571		443		128
	$	4,446	$	2,266	$	2,180	$	4,542	$	2,022	$	2,520

Schedule of estimated future amortization expense on intangible assets

The estimated future amortization for finite-lived intangible assets as of December 31, 2015 is as follows (in millions):

	Risk Solutions		HR Solutions		Total
2016	$	100	$	171	$	271
2017	90		136		226
2018	76		91		167
2019	66		72		138
2020	58		60		118
Thereafter	120		120		240
	$	510	$	650	$	1,160