Loans and Allowance for Loan Losses (Details 4) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Summary of loans, by class
Total non-accrual loans	$ 960,954	$ 925,211
Accruing loans delinquent 90 days or more	103,631	97,476
Total non-performing loans	1,064,585	1,022,687
One- to four-family, Amortizing [Member]
Summary of loans, by class
Total non-accrual loans	710,167	700,429
Accruing loans delinquent 90 days or more	103,631	97,476
One- to four-family, Interest-only [Member]
Summary of loans, by class
Total non-accrual loans	237,408	213,862
Multi-family and commercial mortgages [Member]
Summary of loans, by class
Total non-accrual loans	3,121	2,223
Construction loans [Member]
Summary of loans, by class
Total non-accrual loans	4,296	4,344
Fixed-rate second mortgages [Member]
Summary of loans, by class
Total non-accrual loans	1,017	728
Home equity credit lines [Member]
Summary of loans, by class
Total non-accrual loans	3,945	3,605
Other Loan [Member]
Summary of loans, by class
Total non-accrual loans	$ 1,000	$ 20