Variable Interest Entities ("VIE's") (CLN Structures Summary Information ) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013 item country entity
Credit Linked Note Structure December 2006 [Member]
Credit Linked Notes Structures Summary Information [Line Items]
Amount of Issuance	$ 400
Date of Issuance	December 2006
Original attachment point (subordination)	5.50%
Current attachment point (subordination)	4.17%
Maturity	Dec. 20, 2016
Current rating of tranche	BB-
Number of defaults in underlying collateral pool	2
Number of entities	123
Number of countries	20
Credit Linked Note Structure April 2007 [Member]
Credit Linked Notes Structures Summary Information [Line Items]
Amount of Issuance	$ 200
Date of Issuance	April 2007
Original attachment point (subordination)	2.05%
Current attachment point (subordination)	1.48%
Maturity	Mar. 20, 2017
Current rating of tranche	Ba2
Number of defaults in underlying collateral pool	2
Number of entities	99
Number of countries	21