Long-term Funding Composition (Details) (USD $)	0 Months Ended
	Sep. 30, 2008	Dec. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Sep. 30, 2011	Mar. 31, 2011
Long-term Funding
Federal Home Loan Bank Long Term Advances		$ 2,500,297,000	$ 400,375,000
Senior notes, at par		585,000,000	585,000,000
Subordinated debt, at par		0	25,821,000
Other long-term funding and capitalized costs		1,970,000	4,150,000
Total long-term funding		3,087,267,000	1,015,346,000
Long-term Funding (Textuals) [Abstract]
Weighted average interest rate of Long-term advances		0.10%	1.79%
Federal Home Loan Bank Long Term Advances		2,500,297,000	400,375,000
Federal Home Loan Bank Advances		2,700,000,000
Fixed coupon interest rate of subordinated debt	9.25%
Subordinated debentures issued	26,000,000
New senior debt issued				155,000,000	130,000,000	300,000,000
Loans pledged to the FHLB		$ 3,500,000,000
Senior Notes [Member]
Long Term Debt Disclosure [Line Items]
Percentage of interest rate on senior notes				1.875%	5.125%	5.125%