Fair Value Measurements (Details 6) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Additional information relating to asset-backed securities and collateralized debt obligations
Available-for-sale securities backed by collateral	$ 655	$ 818
Collateral Type [Member]
Additional information relating to asset-backed securities and collateralized debt obligations
Trading asset-backed securities and related collateral	274
Available-for-sale securities backed by collateral	655
AAA -A [Member] | Collateral Type [Member]
Additional information relating to asset-backed securities and collateralized debt obligations
Trading asset-backed securities and related collateral	269
Available-for-sale securities backed by collateral	510
BBB -B [Member] | Collateral Type [Member]
Additional information relating to asset-backed securities and collateralized debt obligations
Trading asset-backed securities and related collateral	1
Available-for-sale securities backed by collateral	80
CCC-Unrated [Member] | Collateral Type [Member]
Additional information relating to asset-backed securities and collateralized debt obligations
Trading asset-backed securities and related collateral	4
Available-for-sale securities backed by collateral	65
Level 2 [Member] | Collateral Type [Member]
Additional information relating to asset-backed securities and collateralized debt obligations
Trading collateralized debt obligations and related collateral	55
Level 2 [Member] | Collateral Type [Member] | Alt-A [Member]
Additional information relating to asset-backed securities and collateralized debt obligations
Trading asset-backed securities and related collateral	72
Available-for-sale securities backed by collateral	349
Level 2 [Member] | Collateral Type [Member] | Sub-prime [Member]
Additional information relating to asset-backed securities and collateralized debt obligations
Trading asset-backed securities and related collateral	202
Level 2 [Member] | AAA -A [Member] | Collateral Type [Member]
Additional information relating to asset-backed securities and collateralized debt obligations
Trading collateralized debt obligations and related collateral	55
Available-for-sale securities backed by collateral	305
Level 2 [Member] | AAA -A [Member] | Collateral Type [Member] | Alt-A [Member]
Additional information relating to asset-backed securities and collateralized debt obligations
Trading asset-backed securities and related collateral	71
Available-for-sale securities backed by collateral	205
Level 2 [Member] | AAA -A [Member] | Collateral Type [Member] | Sub-prime [Member]
Additional information relating to asset-backed securities and collateralized debt obligations
Trading asset-backed securities and related collateral	198
Level 2 [Member] | BBB -B [Member] | Sub-prime [Member]
Additional information relating to asset-backed securities and collateralized debt obligations
Available-for-sale securities backed by collateral	1
Level 2 [Member] | BBB -B [Member] | Collateral Type [Member] | Alt-A [Member]
Additional information relating to asset-backed securities and collateralized debt obligations
Trading asset-backed securities and related collateral	1
Available-for-sale securities backed by collateral	79
Level 2 [Member] | CCC-Unrated [Member] | Sub-prime [Member]
Additional information relating to asset-backed securities and collateralized debt obligations
Available-for-sale securities backed by collateral	1
Level 2 [Member] | CCC-Unrated [Member] | Collateral Type [Member]
Additional information relating to asset-backed securities and collateralized debt obligations
Available-for-sale securities backed by collateral	305
Level 2 [Member] | CCC-Unrated [Member] | Collateral Type [Member] | Alt-A [Member]
Additional information relating to asset-backed securities and collateralized debt obligations
Available-for-sale securities backed by collateral	65
Level 2 [Member] | CCC-Unrated [Member] | Collateral Type [Member] | Sub-prime [Member]
Additional information relating to asset-backed securities and collateralized debt obligations
Trading asset-backed securities and related collateral	4
Level 3 [Member] | Collateral Type [Member]
Additional information relating to asset-backed securities and collateralized debt obligations
Trading collateralized debt obligations and related collateral	699
Level 3 [Member] | BBB -B [Member] | Collateral Type [Member]
Additional information relating to asset-backed securities and collateralized debt obligations
Trading collateralized debt obligations and related collateral	635
Level 3 [Member] | CCC-Unrated [Member] | Collateral Type [Member]
Additional information relating to asset-backed securities and collateralized debt obligations
Trading collateralized debt obligations and related collateral	64
Residential mortgages [Member] | AAA -A [Member] | Collateral Type [Member]
Additional information relating to asset-backed securities and collateralized debt obligations
Trading asset-backed securities and related collateral	269
Available-for-sale securities backed by collateral	3
Residential mortgages [Member] | BBB -B [Member] | Collateral Type [Member]
Additional information relating to asset-backed securities and collateralized debt obligations
Trading asset-backed securities and related collateral	1
Residential mortgages [Member] | CCC-Unrated [Member] | Collateral Type [Member]
Additional information relating to asset-backed securities and collateralized debt obligations
Trading asset-backed securities and related collateral	4
Available-for-sale securities backed by collateral	2
Residential mortgages [Member] | Level 2 [Member] | AAA -A [Member] | Collateral Type [Member] | Alt-A [Member]
Additional information relating to asset-backed securities and collateralized debt obligations
Trading asset-backed securities and related collateral	71
Available-for-sale securities backed by collateral	3
Residential mortgages [Member] | Level 2 [Member] | AAA -A [Member] | Collateral Type [Member] | Sub-prime [Member]
Additional information relating to asset-backed securities and collateralized debt obligations
Trading asset-backed securities and related collateral	198
Residential mortgages [Member] | Level 2 [Member] | BBB -B [Member] | Collateral Type [Member] | Alt-A [Member]
Additional information relating to asset-backed securities and collateralized debt obligations
Trading asset-backed securities and related collateral	1
Residential mortgages [Member] | Level 2 [Member] | CCC-Unrated [Member] | Collateral Type [Member] | Alt-A [Member]
Additional information relating to asset-backed securities and collateralized debt obligations
Available-for-sale securities backed by collateral	2
Residential mortgages [Member] | Level 2 [Member] | CCC-Unrated [Member] | Collateral Type [Member] | Sub-prime [Member]
Additional information relating to asset-backed securities and collateralized debt obligations
Trading asset-backed securities and related collateral	4
Home equity mortgages [Member] | AAA -A [Member] | Collateral Type [Member]
Additional information relating to asset-backed securities and collateralized debt obligations
Available-for-sale securities backed by collateral	108
Home equity mortgages [Member] | CCC-Unrated [Member] | Collateral Type [Member]
Additional information relating to asset-backed securities and collateralized debt obligations
Available-for-sale securities backed by collateral	63
Home equity mortgages [Member] | Level 2 [Member] | AAA -A [Member] | Collateral Type [Member] | Alt-A [Member]
Additional information relating to asset-backed securities and collateralized debt obligations
Available-for-sale securities backed by collateral	108
Home equity mortgages [Member] | Level 2 [Member] | BBB -B [Member] | Collateral Type [Member] | Alt-A [Member]
Additional information relating to asset-backed securities and collateralized debt obligations
Available-for-sale securities backed by collateral	79
Home equity mortgages [Member] | Level 2 [Member] | CCC-Unrated [Member] | Collateral Type [Member] | Alt-A [Member]
Additional information relating to asset-backed securities and collateralized debt obligations
Available-for-sale securities backed by collateral	63
Other securities [Member] | AAA -A [Member] | Collateral Type [Member]
Additional information relating to asset-backed securities and collateralized debt obligations
Available-for-sale securities backed by collateral	85
Other securities [Member] | Level 2 [Member] | AAA -A [Member] | Collateral Type [Member] | Alt-A [Member]
Additional information relating to asset-backed securities and collateralized debt obligations
Available-for-sale securities backed by collateral	85
Other securities [Member] | Level 2 [Member] | BBB -B [Member] | Collateral Type [Member]
Additional information relating to asset-backed securities and collateralized debt obligations
Trading collateralized debt obligations and related collateral	141
Student Loans [Member] | AAA -A [Member] | Collateral Type [Member]
Additional information relating to asset-backed securities and collateralized debt obligations
Available-for-sale securities backed by collateral	9
Student Loans [Member] | Level 2 [Member] | AAA -A [Member] | Collateral Type [Member]
Additional information relating to asset-backed securities and collateralized debt obligations
Trading collateralized debt obligations and related collateral	55
Student Loans [Member] | Level 2 [Member] | AAA -A [Member] | Collateral Type [Member] | Alt-A [Member]
Additional information relating to asset-backed securities and collateralized debt obligations
Available-for-sale securities backed by collateral	9
Commercial Mortgages [Member] | AAA -A [Member] | Collateral Type [Member]
Additional information relating to asset-backed securities and collateralized debt obligations
Available-for-sale securities backed by collateral	305
Commercial Mortgages [Member] | Level 3 [Member] | BBB -B [Member] | Collateral Type [Member]
Additional information relating to asset-backed securities and collateralized debt obligations
Trading collateralized debt obligations and related collateral	163
Commercial Mortgages [Member] | Level 3 [Member] | CCC-Unrated [Member] | Collateral Type [Member]
Additional information relating to asset-backed securities and collateralized debt obligations
Trading collateralized debt obligations and related collateral	64
Corporate Loans [Member] | Level 3 [Member] | BBB -B [Member] | Collateral Type [Member]
Additional information relating to asset-backed securities and collateralized debt obligations
Trading collateralized debt obligations and related collateral	$ 331