Additional Information Regarding Impaired Loans (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2012	Dec. 31, 2011
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance, Recorded Investment	$ 280,008	$ 318,160
Impaired loans with no related allowance, Unpaid Principal Balance	311,199	335,739
Impaired loans with no related allowance, Average Recorded Investment	293,220	436,717
Impaired loans with no related allowance, Interest Income Recognized	6,057	6,043
Impaired loans with an allowance recorded, Recorded Investment	40,333	12,262
Impaired loans with an allowance recorded, Unpaid Principal Balance	41,213	13,129
Impaired loans with an allowance recorded, Related Allowance	1,677	490
Impaired loans with an allowance recorded, Average Recorded Investment	36,474	37,593
Impaired loans with an allowance recorded, Interest Income Recognized	734	187
Total impaired loans, Recorded Investment	320,341	330,422
Total impaired loans, Unpaid Principal Balance	352,412	348,868
Total impaired loans, Related Allowance	1,677	490
Total impaired loans, Average Recorded Investment	329,694	474,310
Total impaired loans, Interest Income Recognized	6,791	6,230
Multi-Family
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance, Recorded Investment	158,750	235,100
Impaired loans with no related allowance, Unpaid Principal Balance	176,801	244,684
Impaired loans with no related allowance, Average Recorded Investment	188,180	321,994
Impaired loans with no related allowance, Interest Income Recognized	2,642	3,435
Impaired loans with an allowance recorded, Recorded Investment	38,488	6,329
Impaired loans with an allowance recorded, Unpaid Principal Balance	39,368	6,899
Impaired loans with an allowance recorded, Related Allowance	1,628	408
Impaired loans with an allowance recorded, Average Recorded Investment	30,423	10,893
Impaired loans with an allowance recorded, Interest Income Recognized	655	187
Total impaired loans, Recorded Investment	197,238	241,429
Total impaired loans, Unpaid Principal Balance	216,169	251,583
Total impaired loans, Related Allowance	1,628	408
Total impaired loans, Average Recorded Investment	218,603	332,887
Total impaired loans, Interest Income Recognized	3,297	3,622
Commercial Real Estate
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance, Recorded Investment	79,744	49,258
Impaired loans with no related allowance, Unpaid Principal Balance	81,237	52,152
Impaired loans with no related allowance, Average Recorded Investment	69,544	63,032
Impaired loans with no related allowance, Interest Income Recognized	1,030	1,397
Impaired loans with an allowance recorded, Recorded Investment	1,845	5,648
Impaired loans with an allowance recorded, Unpaid Principal Balance	1,845	5,857
Impaired loans with an allowance recorded, Related Allowance	49	53
Impaired loans with an allowance recorded, Average Recorded Investment	3,953	10,297
Impaired loans with an allowance recorded, Interest Income Recognized	79
Total impaired loans, Recorded Investment	81,589	54,906
Total impaired loans, Unpaid Principal Balance	83,082	58,009
Total impaired loans, Related Allowance	49	53
Total impaired loans, Average Recorded Investment	73,497	73,329
Total impaired loans, Interest Income Recognized	1,109	1,397
Acquisition, Development and Construction
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance, Recorded Investment	22,643	26,680
Impaired loans with no related allowance, Unpaid Principal Balance	27,015	27,143
Impaired loans with no related allowance, Average Recorded Investment	24,538	42,600
Impaired loans with no related allowance, Interest Income Recognized	636	1,141
Impaired loans with an allowance recorded, Average Recorded Investment	2,098	14,495
Total impaired loans, Recorded Investment	22,643	26,680
Total impaired loans, Unpaid Principal Balance	27,015	27,143
Total impaired loans, Average Recorded Investment	26,636	57,095
Total impaired loans, Interest Income Recognized	636	1,141
One-to-four family
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance, Recorded Investment	1,102	1,127
Impaired loans with no related allowance, Unpaid Principal Balance	1,147	1,520
Impaired loans with no related allowance, Average Recorded Investment	1,118	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
Impaired loans with an allowance recorded, Related Allowance		29
Impaired loans with an allowance recorded, Average Recorded Investment		71
Total impaired loans, Recorded Investment	1,102	1,412
Total impaired loans, Unpaid Principal Balance	1,147	1,893
Total impaired loans, Related Allowance		29
Total impaired loans, Average Recorded Investment	1,118	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	17,769	5,995
Impaired loans with no related allowance, Unpaid Principal Balance	24,999	10,240
Impaired loans with no related allowance, Average Recorded Investment	9,840	6,442
Impaired loans with no related allowance, Interest Income Recognized	1,749	60
Impaired loans with an allowance recorded, Average Recorded Investment		1,837
Total impaired loans, Recorded Investment	17,769	5,995
Total impaired loans, Unpaid Principal Balance	24,999	10,240
Total impaired loans, Average Recorded Investment	9,840	8,279
Total impaired loans, Interest Income Recognized	$ 1,749	$ 60