Goodwill and Other Intangible Assets Schedule of estimated future amortization expense on intangible assets (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013
Finite-Lived Intangible Assets [Line Items]
2014	$ 341
2015	295
2016	249
2017	200
2018	136
Thereafter	338
Total future amortization of intangible assets	1,559
Risk Solutions [Member]
Finite-Lived Intangible Assets [Line Items]
2014	98
2015	83
2016	72
2017	59
2018	42
Thereafter	76
Total future amortization of intangible assets	430
HR Solutions [Member]
Finite-Lived Intangible Assets [Line Items]
2014	243
2015	212
2016	177
2017	141
2018	94
Thereafter	262
Total future amortization of intangible assets	$ 1,129