Additional Information Regarding Impaired Loans (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2012	Dec. 31, 2011
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance, Recorded Investment	$ 281,640	$ 318,160
Impaired loans with no related allowance, Unpaid Principal Balance	308,094	335,739
Impaired loans with no related allowance, Average Recorded Investment	286,668	436,717
Impaired loans with no related allowance, Interest Income Recognized	3,582	6,043
Impaired loans with an allowance recorded, Recorded Investment	50,132	12,262
Impaired loans with an allowance recorded, Unpaid Principal Balance	52,765	13,129
Related Allowance	3,540	490
Impaired loans with an allowance recorded, Average Recorded Investment	27,022	37,593
Impaired loans with an allowance recorded, Interest Income Recognized		187
Total impaired loans, Recorded Investment	331,772	330,422
Total impaired loans, Unpaid Principal Balance	360,859	348,868
Related Allowance	3,540	490
Total impaired loans, Average Recorded Investment	313,690	474,310
Total impaired loans, Interest Income Recognized	3,582	6,230
Multi-Family
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance, Recorded Investment	173,937	235,100
Impaired loans with no related allowance, Unpaid Principal Balance	190,177	244,684
Impaired loans with no related allowance, Average Recorded Investment	194,266	321,994
Impaired loans with no related allowance, Interest Income Recognized	2,641	3,435
Impaired loans with an allowance recorded, Recorded Investment	44,543	6,329
Impaired loans with an allowance recorded, Unpaid Principal Balance	46,014	6,899
Related Allowance	2,907	408
Impaired loans with an allowance recorded, Average Recorded Investment	19,704	10,893
Impaired loans with an allowance recorded, Interest Income Recognized		187
Total impaired loans, Recorded Investment	218,480	241,429
Total impaired loans, Unpaid Principal Balance	236,191	251,583
Related Allowance	2,907	408
Total impaired loans, Average Recorded Investment	213,970	332,887
Total impaired loans, Interest Income Recognized	2,641	3,622
Commercial Real Estate
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance, Recorded Investment	78,661	49,258
Impaired loans with no related allowance, Unpaid Principal Balance	80,086	52,152
Impaired loans with no related allowance, Average Recorded Investment	59,382	63,032
Impaired loans with no related allowance, Interest Income Recognized	518	1,397
Impaired loans with an allowance recorded, Recorded Investment	4,373	5,648
Impaired loans with an allowance recorded, Unpaid Principal Balance	5,257	5,857
Related Allowance	605	53
Impaired loans with an allowance recorded, Average Recorded Investment	5,220	10,297
Total impaired loans, Recorded Investment	83,034	54,906
Total impaired loans, Unpaid Principal Balance	85,343	58,009
Related Allowance	605	53
Total impaired loans, Average Recorded Investment	64,602	73,329
Total impaired loans, Interest Income Recognized	518	1,397
Acquisition, Development and Construction
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance, Recorded Investment	21,610	26,680
Impaired loans with no related allowance, Unpaid Principal Balance	25,704	27,143
Impaired loans with no related allowance, Average Recorded Investment	25,884	42,600
Impaired loans with no related allowance, Interest Income Recognized	366	1,141
Impaired loans with an allowance recorded, Recorded Investment	1,216
Impaired loans with an allowance recorded, Unpaid Principal Balance	1,494
Related Allowance	28
Impaired loans with an allowance recorded, Average Recorded Investment	2,098	14,495
Total impaired loans, Recorded Investment	22,826	26,680
Total impaired loans, Unpaid Principal Balance	27,198	27,143
Related Allowance	28
Total impaired loans, Average Recorded Investment	27,982	57,095
Total impaired loans, Interest Income Recognized	366	1,141
One-to-four family
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance, Recorded Investment	1,127	1,127
Impaired loans with no related allowance, Unpaid Principal Balance	1,147	1,520
Impaired loans with no related allowance, Average Recorded Investment	1,221	2,649
Impaired loans with no related allowance, Interest Income Recognized		10
Impaired loans with an allowance recorded, Recorded Investment		285
Impaired loans with an allowance recorded, Unpaid Principal Balance		373
Related Allowance		29
Impaired loans with an allowance recorded, Average Recorded Investment		71
Total impaired loans, Recorded Investment	1,127	1,412
Total impaired loans, Unpaid Principal Balance	1,147	1,893
Related Allowance		29
Total impaired loans, Average Recorded Investment	1,221	2,720
Total impaired loans, Interest Income Recognized		10
Commercial and Industrial
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance, Recorded Investment	6,305	5,995
Impaired loans with no related allowance, Unpaid Principal Balance	10,980	10,240
Impaired loans with no related allowance, Average Recorded Investment	5,915	6,442
Impaired loans with no related allowance, Interest Income Recognized	57	60
Impaired loans with an allowance recorded, Average Recorded Investment		1,837
Total impaired loans, Recorded Investment	6,305	5,995
Total impaired loans, Unpaid Principal Balance	10,980	10,240
Total impaired loans, Average Recorded Investment	5,915	8,279
Total impaired loans, Interest Income Recognized	$ 57	$ 60