Investment Securities (Weighted-Average Expected Maturity of Mortgage and Other Asset-Backed Debt Securities) (Details)	3 Months Ended
	Sep. 30, 2011
Residential Mortgage-backed Securities [Member] | Mortgage-backed Securities Agency [Member]
Mortgage And Other Asset Backed Securities [Line Items]
Weighted average expected maturity	3.5
Residential Mortgage-backed Securities [Member] | Mortgage-backed Securities Non-agency [Member]
Mortgage And Other Asset Backed Securities [Line Items]
Weighted average expected maturity	4.5
Commercial Mortgage Backed Securities [Member] | Mortgage-backed Securities Agency [Member]
Mortgage And Other Asset Backed Securities [Line Items]
Weighted average expected maturity	5.4
Commercial Mortgage Backed Securities [Member] | Mortgage-backed Securities Non-agency [Member]
Mortgage And Other Asset Backed Securities [Line Items]
Weighted average expected maturity	2.7
Asset backed [Member]
Mortgage And Other Asset Backed Securities [Line Items]
Weighted average expected maturity	3.4