Quality of Non-Covered Loans (Excluding PCI Loans and Leases) (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	$ 7,064,535
Non-Covered Loans	41,844,019	$ 40,133,861
Financing Receivable, 30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		530,000,000
Multi-Family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-Covered Loans	31,158,672	29,883,919
Multi-Family | Financing Receivable, 30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,131
Commercial Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-Covered Loans	7,081,910	6,998,834
One-to-four family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-Covered Loans	380,361	446,094
Acquisition, development, and construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-Covered Loans	200,596	407,870
Commercial and Industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non- Accrual	194,000,000
Non-Covered Loans	3,014,378	2,388,420
Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Non-Covered Loans	8,102	8,724
Non-Covered Loans
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	64,963	46,070
Non- Accrual	61,243	45,506
Current	41,779,056	40,087,791
Non-Covered Loans | Financing Receivable, 30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	3,720	564
Non-Covered Loans | Multi-Family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	6,538	4,220
Non- Accrual	5,407	4,220
Current	31,152,134	29,879,699
Non-Covered Loans | Commercial Real Estate
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	17,375	3,021
Non- Accrual	14,830	3,021
Current		6,995,813
Non-Covered Loans | Commercial Real Estate | Financing Receivable, 30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	2,545
Non-Covered Loans | One-to-four family
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	1,730	1,660
Non- Accrual	1,730	1,651
Current	378,631	444,434
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		9
Non-Covered Loans | Acquisition, development, and construction
Financing Receivable, Recorded Investment, Past Due [Line Items]
Current	200,596	407,870
Non-Covered Loans | Commercial and Industrial
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	39,024	37,138
Non- Accrual	39,024	36,608
Current	2,975,354	2,351,282
Non-Covered Loans | Commercial and Industrial | Financing Receivable, 30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due		530
Non-Covered Loans | Other
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	296	31
Non- Accrual	252	6
Current	7,806	8,693
Non-Covered Loans | Other | Financing Receivable, 30-89 Days Past Due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total Past Due	$ 44	$ 25