Note 13 - Fair Value of Financial Instruments (Details) - Assets and Liabilities Measured at Fair Value on a Recurring Basis (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014		Dec. 31, 2013
Investment securities available for sale:
Investment Securities Available for Sale	$ 892,251		$ 912,443
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale:
Investment Securities Available for Sale	809,137		876,874
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale:
Investment Securities Available for Sale	809,137		876,874
Mortgage-backed Securities, Issued by Private Enterprises [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale:
Investment Securities Available for Sale	2,040		2,361
Mortgage-backed Securities, Issued by Private Enterprises [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale:
Investment Securities Available for Sale	2,040		2,361
Commercial Mortgage Backed Securities [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale:
Investment Securities Available for Sale	45,953
Commercial Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale:
Investment Securities Available for Sale	45,953
Collateralized Debt Obligations [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale:
Investment Securities Available for Sale	35,121		33,208
Collateralized Debt Obligations [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale:
Investment Securities Available for Sale	35,121		33,208
Collateralized Mortgage Backed Securities Held In Securitization Trusts [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale:
Investment Securities Available for Sale	38,379		92,578
Collateralized Mortgage Backed Securities Held In Securitization Trusts [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale:
Investment Securities Available for Sale	38,379		92,578
Multi-Family Loans Held in Securitization Trusts [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale:
Multi-family loans held in securitization trusts	8,303,169		8,111,022
Multi-Family Loans Held in Securitization Trusts [Member] | Fair Value, Measurements, Recurring [Member]
Investment securities available for sale:
Multi-family loans held in securitization trusts	8,303,169		8,111,022
Multi-Family Collateralized Debt Obligations [Member] | Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Liabilities carried at fair value
Multi-family collateralized debt obligations	8,005,013		7,871,020
Multi-Family Collateralized Debt Obligations [Member] | Fair Value, Measurements, Recurring [Member]
Liabilities carried at fair value
Multi-family collateralized debt obligations	8,005,013		7,871,020
TBA Securities [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Derivative assets:
Derivative assets	214,711		190,742
TBA Securities [Member] | Fair Value, Measurements, Recurring [Member]
Derivative assets:
Derivative assets	214,711		190,742
US Treasury Futures Options [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Derivative assets:
Derivative assets			7
US Treasury Futures Options [Member] | Fair Value, Measurements, Recurring [Member]
Derivative assets:
Derivative assets			7
US Treasury Futures [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Derivative assets:
Derivative assets			3,257
Derivative liabilities:
Derivative liabilities	49
US Treasury Futures [Member] | Fair Value, Measurements, Recurring [Member]
Derivative assets:
Derivative assets			3,257
Derivative liabilities:
Derivative liabilities	49
Future [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Derivative assets:
Derivative assets	476		238
Future [Member] | Fair Value, Measurements, Recurring [Member]
Derivative assets:
Derivative assets	476		238
Interest Rate Swap [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Derivative assets:
Derivative assets	1,892		2,041
Interest Rate Swap [Member] | Fair Value, Measurements, Recurring [Member]
Derivative assets:
Derivative assets	1,892		2,041
Swaption [Member] | Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Derivative assets:
Derivative assets	245		1,305
Swaption [Member] | Fair Value, Measurements, Recurring [Member]
Derivative assets:
Derivative assets	245		1,305
Eurodollar Future [Member] | Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Derivative liabilities:
Derivative liabilities	370		1,432
Eurodollar Future [Member] | Fair Value, Measurements, Recurring [Member]
Derivative liabilities:
Derivative liabilities	370		1,432
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Derivative assets:
Total	476		3,502
Derivative liabilities:
Total	419		1,432
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Derivative assets:
Total	1,063,146		1,106,531
Fair Value, Inputs, Level 2 [Member]
Investment securities available for sale:
Investment Securities Available for Sale	892,251	[1]	912,443	[1]
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Derivative assets:
Total	8,387,501		8,203,600
Derivative liabilities:
Total	8,005,013		7,871,020
Fair Value, Measurements, Recurring [Member]
Derivative assets:
Total	9,451,123		9,313,633
Derivative liabilities:
Total	$ 8,005,432		$ 7,872,452

[1] Includes $46.0 million of CMBS securities classified as level 3.