Average Recorded Investment, Interest Income Recognized and Cash Basis Interest Income Related to Impaired Loans by Segment and Class (Detail) (USD $) In Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2011	Jun. 30, 2011
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	$ 310,307	$ 307,072
Interest Income Recognized	2,035	4,124
Cash Basis Interest Income	2,241	4,386
One to Four Family | Full Documentation Interest Only Loans | With an allowance recorded
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	10,498	10,676
Interest Income Recognized	101	216
Cash Basis Interest Income	115	216
One to Four Family | Full Documentation Amortizing Loans | With an allowance recorded
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	5,943	6,409
Interest Income Recognized	50	86
Cash Basis Interest Income	44	83
One to Four Family | Reduced Documentation Interest Only Loans | With an allowance recorded
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	11,268	10,923
Interest Income Recognized	105	257
Cash Basis Interest Income	117	270
One to Four Family | Reduced Documentation Amortizing Loans | With an allowance recorded
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	1,186	1,135
Interest Income Recognized	11	24
Cash Basis Interest Income	11	23
Multi Family | With an allowance recorded
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	54,409	53,301
Interest Income Recognized	542	1,280
Cash Basis Interest Income	626	1,310
Commercial Real Estate | With an allowance recorded
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	19,896	19,539
Interest Income Recognized	334	665
Cash Basis Interest Income	318	651
Construction | With an allowance recorded
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	6,121	6,225
Interest Income Recognized	25	56
Cash Basis Interest Income	28	59
One to Four Family | Full Documentation Interest Only Loans | Without an allowance recorded
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	65,421	65,009
Interest Income Recognized	258	459
Cash Basis Interest Income	322	590
One to Four Family | Full Documentation Amortizing Loans | Without an allowance recorded
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	12,882	12,549
Interest Income Recognized	14	18
Cash Basis Interest Income	22	36
One to Four Family | Reduced Documentation Interest Only Loans | Without an allowance recorded
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	107,999	107,301
Interest Income Recognized	548	958
Cash Basis Interest Income	583	1,032
One to Four Family | Reduced Documentation Amortizing Loans | Without an allowance recorded
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	14,045	13,366
Interest Income Recognized	47	105
Cash Basis Interest Income	55	116
Construction | Without an allowance recorded
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	$ 639	$ 639