Investment Securities (Mortgage-backed, Asset-backed Securities) (Details)	9 Months Ended
Sep. 30, 2013
Fixed rate CMBS
Investment securities
Average basis points of subordination	0.25
Maximum \| Commercial Mortgage Backed Securities
Investment securities
Percentage of underlying loans reported as non-performing	1.00%

Reflects the percentage derived from dividing impaired loans on which interest has ceased to be accrued by total loans.

No definition available.

Name:	us-gaap_LoansAndLeasesReceivableRatioOfNonperformingLoansToAllLoans
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant