Loans and Allowance for Loan Losses (Details 1) (USD $) In Thousands	Sep. 30, 2011	Dec. 31, 2010
Loan portfolio by credit quality indicator
Performing	$ 29,098,716	$ 30,052,638
Non-performing	948,706	871,259
Total	30,047,422	30,923,897
One- to four-family, Amortizing [Member]
Loan portfolio by credit quality indicator
Performing	24,070,010	24,733,745
Non-performing	736,751	678,914
Total	24,806,761	25,412,659
Pass	23,963,790	24,646,101
Special mention	151,673	151,800
Substandard	690,698	614,758
Doubtful	600	0
Total	24,806,761	25,412,659
One- to four-family, Interest-only [Member]
Loan portfolio by credit quality indicator
Performing	4,697,894	4,957,115
Non-performing	199,696	179,348
Total	4,897,590	5,136,463
Pass	4,664,834	4,927,545
Special mention	30,576	29,570
Substandard	202,180	179,348
Doubtful	0	0
Total	4,897,590	5,136,463
Multi-family and commercial mortgages [Member]
Loan portfolio by credit quality indicator
Performing	39,433	46,950
Non-performing	525	1,117
Total	39,958	48,067
Pass	24,164	37,697
Special mention	2,561	1,199
Substandard	4,188	1,117
Doubtful	9,045	8,054
Total	39,958	48,067
Construction [Member]
Loan portfolio by credit quality indicator
Performing	1,097	1,521
Non-performing	6,902	7,560
Total	7,999	9,081
Pass	0	1,521
Special mention	1,097	0
Substandard	5,202	7,560
Doubtful	1,700	0
Total	7,999	9,081
Fixed-rate second mortgages [Member]
Loan portfolio by credit quality indicator
Performing	138,200	160,456
Non-performing	567	440
Total	138,767	160,896
Pass	137,576	160,216
Special mention	624	240
Substandard	567	440
Doubtful	0	0
Total	138,767	160,896
Home equity credit lines [Member]
Loan portfolio by credit quality indicator
Performing	132,228	135,111
Non-performing	3,644	2,356
Total	135,872	137,467
Pass	131,653	134,408
Special mention	575	703
Substandard	3,552	2,356
Doubtful	92	0
Total	135,872	137,467
Other [Member]
Loan portfolio by credit quality indicator
Performing	19,854	17,740
Non-performing	621	1,524
Total	20,475	19,264
Pass	19,200	17,737
Special mention	654	3
Substandard	621	1,524
Doubtful	0	0
Total	$ 20,475	$ 19,264