Quality of Non-Covered Loans (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-Covered Loans	$ 33,004,361		$ 29,821,715
Multi-Family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non- Accrual			3,900
Non-Covered Loans	23,831,846		20,699,927
Commercial Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non- Accrual			1,100
Non-Covered Loans	7,634,320		7,364,231
One-to-four family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-Covered Loans	138,915		560,730
Acquisition, Development and Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-Covered Loans	258,116		344,100
Commercial and Industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non- Accrual			758
Non-Covered Loans	1,109,221	[1],[2]	813,691	[1],[2]
Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-Covered Loans	31,943		39,036
Non-Covered Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	6,192		37,089
Non- Accrual	76,950		103,537
Total Past Due	83,142		140,626
Current	32,921,219		29,681,089
Non-Covered Loans | Multi-Family
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	464		33,678
Non- Accrual	31,089		58,395
Total Past Due	31,553		92,073
Current	23,800,293		20,607,854
Non-Covered Loans | Commercial Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	1,464		1,854
Non- Accrual	24,824		24,550
Total Past Due	26,288		26,404
Current	7,608,032		7,337,827
Non-Covered Loans | One-to-four family
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	3,086		1,076
Non- Accrual	11,032		10,937
Total Past Due	14,118		12,013
Current	124,797		548,717
Non-Covered Loans | Acquisition, Development and Construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non- Accrual	654		2,571
Total Past Due	654		2,571
Current	257,462		341,529
Non-Covered Loans | Commercial and Industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	530	[1]	1	[1]
Non- Accrual	8,382	[1]	5,735	[1]
Total Past Due	8,912	[1]	5,736	[1]
Current	1,100,309	[1]	807,955	[1]
Non-Covered Loans | Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
30-89 Days Past Due	648		480
Non- Accrual	969		1,349
Total Past Due	1,617		1,829
Current	$ 30,326		$ 37,207

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

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