Loans and Allowance for Loan Losses (Details 1) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010
Loan portfolio by credit quality indicator
Performing	$ 29,459,237	$ 30,052,638
Non-performing	914,239	871,259
Total	30,373,476	30,923,897
One- to four-family, Amortizing [Member]
Loan portfolio by credit quality indicator
Performing	24,246,317	24,733,745
Non-performing	710,635	678,914
Total	24,956,952	25,412,659
Pass	24,190,053	24,646,101
Special mention	131,009	151,800
Substandard	635,290	614,758
Doubtful	600	0
Total	24,956,952	25,412,659
One- to four-family, Interest-only [Member]
Loan portfolio by credit quality indicator
Performing	4,873,257	4,957,115
Non-performing	192,283	179,348
Total	5,065,540	5,136,463
Pass	4,846,639	4,927,545
Special mention	26,618	29,570
Substandard	192,283	179,348
Doubtful	0	0
Total	5,065,540	5,136,463
Multi-family and commercial mortgages [Member]
Loan portfolio by credit quality indicator
Performing	41,929	46,950
Non-performing	531	1,117
Total	42,460	48,067
Pass	25,705	37,697
Special mention	3,480	1,199
Substandard	4,228	1,117
Doubtful	9,047	8,054
Total	42,460	48,067
Construction [Member]
Loan portfolio by credit quality indicator
Performing	1,366	1,521
Non-performing	7,002	7,560
Total	8,368	9,081
Pass	0	1,521
Special mention	1,366	0
Substandard	5,302	7,560
Doubtful	1,700	0
Total	8,368	9,081
Fixed-rate second mortgages [Member]
Loan portfolio by credit quality indicator
Performing	144,284	160,456
Non-performing	462	440
Total	144,746	160,896
Pass	144,067	160,216
Special mention	217	240
Substandard	462	440
Doubtful	0	0
Total	144,746	160,896
Home equity credit lines [Member]
Loan portfolio by credit quality indicator
Performing	131,422	135,111
Non-performing	3,266	2,356
Total	134,688	137,467
Pass	130,833	134,408
Special mention	589	703
Substandard	3,174	2,356
Doubtful	92	0
Total	134,688	137,467
Other [Member]
Loan portfolio by credit quality indicator
Performing	20,662	17,740
Non-performing	60	1,524
Total	20,722	19,264
Pass	19,848	17,737
Special mention	814	3
Substandard	60	1,524
Doubtful	0	0
Total	$ 20,722	$ 19,264