Non-Covered Loan Portfolio by Credit Quality Indicator (Detail) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010
Financing Receivable, Recorded Investment [Line Items]
Non-Covered Loans	$ 24,496,616	$ 23,714,675
Multi-Family
Financing Receivable, Recorded Investment [Line Items]
Non-Covered Loans	17,055,571	16,807,913
Multi-Family | Pass
Financing Receivable, Recorded Investment [Line Items]
Non-Covered Loans	16,602,460	16,097,834
Multi-Family | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Non-Covered Loans	56,001	172,713
Multi-Family | Substandard
Financing Receivable, Recorded Investment [Line Items]
Non-Covered Loans	397,015	535,366
Multi-Family | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Non-Covered Loans	95	2,000
Commercial Real Estate
Financing Receivable, Recorded Investment [Line Items]
Non-Covered Loans	6,123,594	5,439,611
Commercial Real Estate | Pass
Financing Receivable, Recorded Investment [Line Items]
Non-Covered Loans	5,930,036	5,239,936
Commercial Real Estate | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Non-Covered Loans	66,810	22,650
Commercial Real Estate | Substandard
Financing Receivable, Recorded Investment [Line Items]
Non-Covered Loans	126,748	176,797
Commercial Real Estate | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Non-Covered Loans		228
Acquisition, Development and Construction
Financing Receivable, Recorded Investment [Line Items]
Non-Covered Loans	524,077	569,537
Acquisition, Development and Construction | Pass
Financing Receivable, Recorded Investment [Line Items]
Non-Covered Loans	434,077	454,570
Acquisition, Development and Construction | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Non-Covered Loans	21,968	6,650
Acquisition, Development and Construction | Substandard
Financing Receivable, Recorded Investment [Line Items]
Non-Covered Loans	68,032	108,317
One to Four Family
Financing Receivable, Recorded Investment [Line Items]
Non-Covered Loans	148,194	170,392
One to Four Family | Pass
Financing Receivable, Recorded Investment [Line Items]
Non-Covered Loans	136,458	158,240
One to Four Family | Substandard
Financing Receivable, Recorded Investment [Line Items]
Non-Covered Loans	11,736	12,152
Mortgage Receivable
Financing Receivable, Recorded Investment [Line Items]
Non-Covered Loans	23,851,436	22,987,453
Mortgage Receivable | Pass
Financing Receivable, Recorded Investment [Line Items]
Non-Covered Loans	23,103,031	21,950,580
Mortgage Receivable | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Non-Covered Loans	144,779	202,013
Mortgage Receivable | Substandard
Financing Receivable, Recorded Investment [Line Items]
Non-Covered Loans	603,531	832,632
Mortgage Receivable | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Non-Covered Loans	95	2,228
Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Non-Covered Loans	571,200	641,663
Commercial and Industrial | Pass
Financing Receivable, Recorded Investment [Line Items]
Non-Covered Loans	537,415	594,373
Commercial and Industrial | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Non-Covered Loans	16,626	21,224
Commercial and Industrial | Substandard
Financing Receivable, Recorded Investment [Line Items]
Non-Covered Loans	17,159	23,564
Commercial and Industrial | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Non-Covered Loans		2,502
Other
Financing Receivable, Recorded Investment [Line Items]
Non-Covered Loans	73,980	85,559
Other | Pass
Financing Receivable, Recorded Investment [Line Items]
Non-Covered Loans	71,924	83,887
Other | Substandard
Financing Receivable, Recorded Investment [Line Items]
Non-Covered Loans	2,056	1,672
Total Other Loan Segment
Financing Receivable, Recorded Investment [Line Items]
Non-Covered Loans	645,180	727,222
Total Other Loan Segment | Pass
Financing Receivable, Recorded Investment [Line Items]
Non-Covered Loans	609,339	678,260
Total Other Loan Segment | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Non-Covered Loans	16,626	21,224
Total Other Loan Segment | Substandard
Financing Receivable, Recorded Investment [Line Items]
Non-Covered Loans	19,215	25,236
Total Other Loan Segment | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Non-Covered Loans		$ 2,502