Quality of Non-Covered Loans (Detail) - USD ($) $ in Thousands		Sep. 30, 2015		Dec. 31, 2014		Sep. 30, 2014
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-Covered Loans		$ 34,124,905		$ 33,004,361
Multi-Family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-Covered Loans		24,635,567		23,831,846
Commercial Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non- Accrual						$ 2,100
Non-Covered Loans		7,642,994		7,634,320
One-to-four family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-Covered Loans		102,317		138,915
Acquisition, Development and Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non- Accrual						935
Non-Covered Loans		294,768		258,116
Commercial and Industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non- Accrual						$ 499
Non-Covered Loans	[1]	1,410,214		1,109,221	[2]
Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-Covered Loans		26,069		31,943
Non-Covered Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non- Accrual		55,242	[3]	76,950
Total Past Due		62,829		83,142
Current		34,049,100		32,921,219
Non-Covered Loans | Financing Receivable, 30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		7,587		6,192
Non-Covered Loans | Multi-Family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non- Accrual		15,524	[3]	31,089
Total Past Due		17,194		31,553
Current		24,618,373		23,800,293
Non-Covered Loans | Multi-Family | Financing Receivable, 30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		1,670		464
Non-Covered Loans | Commercial Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non- Accrual		20,034	[3]	24,824
Total Past Due		24,578		26,288
Current		7,618,416		7,608,032
Non-Covered Loans | Commercial Real Estate | Financing Receivable, 30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		4,544		1,464
Non-Covered Loans | One-to-four family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non- Accrual		11,445	[3]	11,032
Total Past Due		12,305		14,118
Current		90,012		124,797
Non-Covered Loans | One-to-four family | Financing Receivable, 30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		860		3,086
Non-Covered Loans | Acquisition, Development and Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non- Accrual		525	[3]	654
Total Past Due		525		654
Current		294,243		257,462
Non-Covered Loans | Commercial and Industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non- Accrual	[2]	6,221	[3]	8,382
Total Past Due	[2]	6,221		8,912
Current	[2]	1,403,993		1,100,309
Non-Covered Loans | Commercial and Industrial | Financing Receivable, 30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	[2]			530
Non-Covered Loans | Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non- Accrual		1,493	[3]	969
Total Past Due		2,006		1,617
Current		24,063		30,326
Non-Covered Loans | Other | Financing Receivable, 30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		$ 513		$ 648

[1] Includes lease financing receivables, all of which were classified as "pass."

[2] Includes lease financing receivables, all of which were current.

[3] Excludes $1.1 million of non-covered PCI loans that were 90 days or more past due.