Balances of Loans Receivable by Segment and Impairment Evaluation and Allowance for Loan Losses Associated with such Loans (Detail) (USD $) In Thousands	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Individually evaluated for impairment	$ 1,641,132		$ 1,857,817
Loans Collectively evaluated for impairment	11,787,639		12,281,252
Loans (gross) amount	13,428,771		14,139,069
Loans Individually evaluated for impairment, Allowance for loan losses	54,196		60,750
Loans Collectively evaluated for impairment, Allowance for loan losses	128,521		140,749
Total allowance for loan losses	182,717	189,486	201,499
Mortgage loans (gross)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans (gross) amount	13,134,600		13,829,729
Mortgage loans (gross) | One to Four Family
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Individually evaluated for impairment	321,084		315,994
Loans Collectively evaluated for impairment	10,229,913		10,539,067
Loans (gross) amount	10,550,997		10,855,061
Loans Individually evaluated for impairment, Allowance for loan losses	10,210		12,541
Loans Collectively evaluated for impairment, Allowance for loan losses	104,503		112,983
Total allowance for loan losses	114,713	117,722	125,524
Mortgage loans (gross) | Multi Family
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Individually evaluated for impairment	951,483		1,144,633
Loans Collectively evaluated for impairment	894,570		1,043,236
Loans (gross) amount	1,846,053		2,187,869
Loans Individually evaluated for impairment, Allowance for loan losses	31,089		34,124
Loans Collectively evaluated for impairment, Allowance for loan losses	15,380		18,662
Total allowance for loan losses	46,469	49,396	52,786
Mortgage loans (gross) | Commercial Real Estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Individually evaluated for impairment	358,819		385,904
Loans Collectively evaluated for impairment	364,728		385,750
Loans (gross) amount	723,547		771,654
Loans Individually evaluated for impairment, Allowance for loan losses	10,185		10,784
Loans Collectively evaluated for impairment, Allowance for loan losses	4,385		4,779
Total allowance for loan losses	14,570	14,782	15,563
Mortgage loans (gross) | Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Individually evaluated for impairment	6,445		7,872
Loans Collectively evaluated for impairment	7,558		7,273
Loans (gross) amount	14,003		15,145
Loans Individually evaluated for impairment, Allowance for loan losses	2,662		3,250
Loans Collectively evaluated for impairment, Allowance for loan losses	239		230
Total allowance for loan losses	2,901	3,502	3,480
Consumer and Other Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans Individually evaluated for impairment	3,301		3,414
Loans Collectively evaluated for impairment	290,870		305,926
Loans (gross) amount	294,171		309,340
Loans Individually evaluated for impairment, Allowance for loan losses	50		51
Loans Collectively evaluated for impairment, Allowance for loan losses	4,014		4,095
Total allowance for loan losses	$ 4,064	$ 4,084	$ 4,146