Summary of Significant Accounting Policies (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014 Segment	Sep. 30, 2013	Dec. 31, 2013
Accounting Policies [Abstract]
Number of operating segments			3
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Assets	$ 300,202,000,000		$ 300,202,000,000		$ 296,933,000,000
Liabilities	256,184,000,000		256,184,000,000		255,301,000,000
Retained earnings	23,162,000,000		23,162,000,000		20,292,000,000
Net income	1,081,000,000	1,105,000,000	3,429,000,000	3,269,000,000
Investment recognized, amortization	87,000,000		231,000,000
Investment, tax credits	90,000,000		268,000,000
Carrying value of investments in qualified affordable housing projects	3,000,000,000		3,000,000,000		2,800,000,000
Unfunded commitment liability	1,200,000,000		1,200,000,000
Accounting Standards Update 2014-01
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reduction in net income		12,000,000		31,000,000
Restatement adjustment | Accounting Standards Update 2014-01
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reduction of total assets					115,000,000
Reduction of total liabilities					3,000,000
Reduction of retained interests					112,000,000
Previously reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net income		1,100,000,000		3,300,000,000
Previously reported | Accounting Standards Update 2014-01
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Assets					297,000,000,000
Liabilities					255,300,000,000
Retained earnings					$ 20,400,000,000