Additional Information about Impaired Loans (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance, Recorded Investment	$ 136,811	$ 295,821
Impaired loans with no related allowance, Unpaid Principal Balance	168,775	322,586
Impaired loans with no related allowance, Average Recorded Investment	189,939	293,870
Impaired loans with no related allowance, Interest Income Recognized	4,050	7,804
Impaired loans with an allowance recorded, Recorded Investment	3,049	31,575
Impaired loans with an allowance recorded, Unpaid Principal Balance	3,049	36,306
Impaired loans with an allowance recorded, Related Allowance	828	2,685
Impaired loans with an allowance recorded, Average Recorded Investment	4,456	35,249
Impaired loans with an allowance recorded, Interest Income Recognized		2,305
Total impaired loans, Recorded Investment	139,860	327,396
Total impaired loans, Unpaid Principal Balance	171,824	358,892
Total impaired loans, Related Allowance	828	2,685
Total impaired loans, Average Recorded Investment	194,395	329,119
Total impaired loans, Interest Income Recognized	4,050	10,109
Multi-Family
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance, Recorded Investment	85,843	193,500
Impaired loans with no related allowance, Unpaid Principal Balance	96,852	211,329
Impaired loans with no related allowance, Average Recorded Investment	130,020	189,510
Impaired loans with no related allowance, Interest Income Recognized	1,991	4,929
Impaired loans with an allowance recorded, Recorded Investment	3,049	20,307
Impaired loans with an allowance recorded, Unpaid Principal Balance	3,049	21,620
Impaired loans with an allowance recorded, Related Allowance	828	1,055
Impaired loans with an allowance recorded, Average Recorded Investment	3,256	27,894
Impaired loans with an allowance recorded, Interest Income Recognized		802
Total impaired loans, Recorded Investment	88,892	213,807
Total impaired loans, Unpaid Principal Balance	99,901	232,949
Total impaired loans, Related Allowance	828	1,055
Total impaired loans, Average Recorded Investment	133,276	217,404
Total impaired loans, Interest Income Recognized	1,991	5,731
Commercial Real Estate
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance, Recorded Investment	42,126	80,453
Impaired loans with no related allowance, Unpaid Principal Balance	46,770	81,134
Impaired loans with no related allowance, Average Recorded Investment	47,882	72,271
Impaired loans with no related allowance, Interest Income Recognized	1,604	1,705
Impaired loans with an allowance recorded, Recorded Investment		2,914
Impaired loans with an allowance recorded, Unpaid Principal Balance		2,940
Impaired loans with an allowance recorded, Related Allowance		402
Impaired loans with an allowance recorded, Average Recorded Investment	1,200	3,693
Impaired loans with an allowance recorded, Interest Income Recognized		98
Total impaired loans, Recorded Investment	42,126	83,367
Total impaired loans, Unpaid Principal Balance	46,770	84,074
Total impaired loans, Related Allowance		402
Total impaired loans, Average Recorded Investment	49,082	75,964
Total impaired loans, Interest Income Recognized	1,604	1,803
One-to-four family
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance, Recorded Investment		1,101
Impaired loans with no related allowance, Unpaid Principal Balance		1,147
Impaired loans with no related allowance, Average Recorded Investment	367	1,114
Total impaired loans, Recorded Investment		1,101
Total impaired loans, Unpaid Principal Balance		1,147
Total impaired loans, Average Recorded Investment	367	1,114
Acquisition, Development and Construction
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance, Recorded Investment	2,451	10,203
Impaired loans with no related allowance, Unpaid Principal Balance	2,451	14,297
Impaired loans with no related allowance, Average Recorded Investment	4,815	20,954
Impaired loans with no related allowance, Interest Income Recognized	89	790
Impaired loans with an allowance recorded, Recorded Investment		1,216
Impaired loans with an allowance recorded, Unpaid Principal Balance		1,494
Impaired loans with an allowance recorded, Related Allowance		29
Impaired loans with an allowance recorded, Average Recorded Investment		1,877
Total impaired loans, Recorded Investment	2,451	11,419
Total impaired loans, Unpaid Principal Balance	2,451	15,791
Total impaired loans, Related Allowance		29
Total impaired loans, Average Recorded Investment	4,815	22,831
Total impaired loans, Interest Income Recognized	89	790
Commercial and Industrial
Financing Receivable, Impaired [Line Items]
Impaired loans with no related allowance, Recorded Investment	6,391	10,564
Impaired loans with no related allowance, Unpaid Principal Balance	22,702	14,679
Impaired loans with no related allowance, Average Recorded Investment	6,855	10,021
Impaired loans with no related allowance, Interest Income Recognized	366	380
Impaired loans with an allowance recorded, Recorded Investment		7,138
Impaired loans with an allowance recorded, Unpaid Principal Balance		10,252
Impaired loans with an allowance recorded, Related Allowance		1,199
Impaired loans with an allowance recorded, Average Recorded Investment		1,785
Impaired loans with an allowance recorded, Interest Income Recognized		1,405
Total impaired loans, Recorded Investment	6,391	17,702
Total impaired loans, Unpaid Principal Balance	22,702	24,931
Total impaired loans, Related Allowance		1,199
Total impaired loans, Average Recorded Investment	6,855	11,806
Total impaired loans, Interest Income Recognized	$ 366	$ 1,785