v2.4.0.6
Regulatory Requirements (Capital Measures) (Details) (USD $)
 12 Months Ended
Dec. 31, 2011
Jun. 30, 2012
Balance    
Tier 1 common capital, amount $ 39,785,000,000 [1],[2] $ 42,765,000,000 [1],[2]
Tier 1 capital, amount 51,114,000,000 [1] 54,245,000,000 [1]
Total capital, amount 54,956,000,000 [1] 57,954,000,000 [1]
RWAs 314,827,000,000 [1] 314,800,000,000 [1]
Adjusted average assets 769,578,000,000 [1] 760,831,000,000 [1]
Tier 1 leverage capital, amount 0 [1] 0 [1]
Ratio    
Tier 1 common capital, ratio 12.60% [1],[2] 13.60% [1],[2]
Tier 1 capital to RWAs, ratio 16.20% [1] 17.20% [1]
Total capital to RWAs, ratio 17.50% [1] 18.40% [1]
Tier 1 leverage, ratio 6.60% [1] 7.10% [1]
Increase (decrease) of Tier 1 common capital (4,200,000,000)  
Increase (decrease) of Tier 1 common capital ratio (1.32%)  
Increase (decrease) of Tier 1 leverage ratio (0.20%)  
Change in Deferred Tax Asset Disallowance
    
Ratio    
Increase (decrease) of Tier 1 common capital ratio (0.30%)  
Increase (decrease) of Tier 1 capital ratio (0.30%)  
Increase (decrease) of Total capital ratio (0.30%)  
Increase of deferred tax asset disallowance $ (1,200,000,000)  
[1] The December 31, 2011 deferred tax asset disallowance was adjusted by approximately $1.2 billion, resulting in a reduction to the Company’s Tier 1 common capital, Tier 1 capital, Total capital, RWAs and adjusted average assets by such amount, Tier 1 common capital ratio, Tier 1 capital ratio and Total capital ratio by approximately 30 basis points and Tier 1 leverage ratio by approximately 20 basis points.
[2] Tier 1 common capital ratio equals Tier 1 common capital divided by RWAs. On December 30, 2011, the Federal Reserve formalized regulatory definitions for Tier 1 common capital and Tier 1 common capital ratio. The Federal Reserve defined Tier 1 common capital as Tier 1 capital less non-common elements in Tier 1 capital, including perpetual preferred stock and related surplus, minority interest in subsidiaries, trust preferred securities and mandatory convertible preferred securities. Previously, the Company’s definition of Tier 1 common capital included all of the items noted in the Federal Reserve’s definition, but it also included an adjustment for the portion of goodwill and non-servicing intangible assets associated with MSSB’s noncontrolling interests (i.e., Citigroup, Inc.’s (“Citi”) share of MSSB’s goodwill and intangibles). The Company’s conformance to the Federal Reserve’s definition under the final rule reduced its Tier 1 common capital and Tier 1 common ratio by approximately $4.2 billion and 132 basis points, respectively at December 31, 2011.