Loans Receivable and Allowance for Loan Losses (Details 5) (USD $)	Jun. 30, 2013	Dec. 31, 2012
Recorded Investment
Total	$ 12,608,915,000	$ 13,155,914,000
Residential Mortgage Loans | Interest-only loans
Recorded Investment
Total	2,675,211,000
Residential Mortgage Loans | Interest-only loans | Within one year
Recorded Investment
Total	224,443,000
Residential Mortgage Loans | Interest-only loans | More than one year to three years
Recorded Investment
Total	1,387,809,000
Residential Mortgage Loans | Interest-only loans | More than three years to five years
Recorded Investment
Total	929,416,000
Residential Mortgage Loans | Interest-only loans | Over five years
Recorded Investment
Total	$ 133,543,000