Hardy Schedule of intangible assets acquired (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Jul. 03, 2012
Indefinite-lived intangible assets		$ 55
Finite-lived intangible assets		81
Total intangible assets as of the acquisition date		136
Lloyds syndicate capacity [Member]
Indefinite-lived intangible assets		55
Value of business acquired [Member]
Finite-lived intangible assets		60
Trade Name [Member]
Economic useful life measured in years	8
Finite-lived intangible assets		8
Distribution Rights [Member]
Economic useful life measured in years	15
Finite-lived intangible assets		$ 13
Minimum [Member] | Lloyds syndicate capacity [Member]
Economic useful life measured in years	1
Maximum [Member] | Lloyds syndicate capacity [Member]
Economic useful life measured in years	4