Composition of Loan Portfolio (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014		Dec. 31, 2013		Jun. 30, 2013	Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-Covered Loans	$ 31,966,411		$ 29,821,715
Net deferred loan origination costs	19,529		16,274
Non-Covered Loans, Percentage	100.00%		100.00%
Allowance for losses on non-covered loans	(139,473)		(141,946)		(140,689)	(140,948)
Non-covered loans held for investment, net	31,846,467		29,696,043
Covered loans	2,596,659		2,788,618
Allowance for losses on covered loans	(49,626)		(64,069)		(60,431)	(51,311)
Total covered loans, net	2,547,033		2,724,549
Loans held for sale	308,895		306,915
Total loans, net	34,702,395		32,727,507
Multi-Family
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-Covered Loans	22,310,512		20,699,927
Non-Covered Loans, Percentage	69.79%		69.41%
Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-Covered Loans	7,619,751		7,364,231
Non-Covered Loans, Percentage	23.84%		24.70%
One-to-four family
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-Covered Loans	689,966		560,730
Non-Covered Loans, Percentage	2.16%		1.88%
Covered loans	2,365,543
Acquisition, Development and Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-Covered Loans	343,598		344,100
Non-Covered Loans, Percentage	1.07%		1.15%
Mortgage Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-Covered Loans	30,963,827		28,968,988
Non-Covered Loans, Percentage	96.86%		97.14%
Allowance for losses on non-covered loans	(126,420)		(127,840)		(123,915)	(127,934)
Commercial and Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-Covered Loans	966,888	[1],[2]	813,691	[1],[3]
Commercial and Industrial | Other loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-Covered Loans	860,911		712,260
Non-Covered Loans, Percentage	2.70%		2.39%
Lease financing, unearned income
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-Covered Loans	105,977		101,431
Non-Covered Loans, Percentage	0.33%		0.34%
Total Commercial and Industrial Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-Covered Loans	966,888		813,691
Non-Covered Loans, Percentage	3.03%		2.73%
Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-Covered Loans	35,696		39,036
Non-Covered Loans, Percentage	0.11%		0.13%
Total Other Loan Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Non-Covered Loans	$ 1,002,584		$ 852,727
Non-Covered Loans, Percentage	3.14%		2.86%

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

[2] Includes lease financing receivables, all of which were current at June 30, 2014.

[3] Includes lease financing receivables, all of which were current at December 31, 2013.