Loans and Allowance for Loan Losses (Details) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010
First mortgage loans:
Total first mortgage loans	$ 30,073,320	$ 30,606,270
Consumer and other loans:
Total consumer and other loans	300,156	317,627
Total loans	30,373,476	30,923,897
One- to four-family, Amortizing [Member]
First mortgage loans:
Total first mortgage loans	24,956,952	25,412,659
Consumer and other loans:
Total loans	24,956,952	25,412,659
One- to four-family, Interest-only [Member]
First mortgage loans:
Total first mortgage loans	5,065,540	5,136,463
Consumer and other loans:
Total loans	5,065,540	5,136,463
FHA/VA [Member]
First mortgage loans:
Total first mortgage loans	718,204	499,724
Multi-family and commercial mortgages [Member]
First mortgage loans:
Total first mortgage loans	42,460	48,067
Consumer and other loans:
Total loans	42,460	48,067
Construction loans [Member]
First mortgage loans:
Total first mortgage loans	8,368	9,081
Consumer and other loans:
Total loans	8,368	9,081
Fixed-rate second mortgages [Member]
Consumer and other loans:
Total consumer and other loans	144,746	160,896
Total loans	144,746	160,896
Home equity credit lines [Member]
Consumer and other loans:
Total consumer and other loans	134,688	137,467
Total loans	134,688	137,467
Other [Member]
Consumer and other loans:
Total consumer and other loans	20,722	19,264
Total loans	$ 20,722	$ 19,264