Investment Securities (Securities With Other-Than-Temporary Impairment, Cumulative Other-Than-Temporary Impairment) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Investment [Line Items]
Amortized Cost	$ 2,030,801		$ 1,953,842
Amount of other-than-temporary impairment recognized in earnings	3,252		5,060		68,090
Total other-than-temporary-impairment recognized in earnings	1,409		3,927		24,795
Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Investment [Line Items]
Amortized Cost	66,907
Amount of other-than-temporary impairment recognized in earnings	521		2,997		4,429
Pooled Trust Preferred Securities Group 2 [Member]
Investment [Line Items]
Amortized Cost	11,223
Amount of other-than-temporary impairment recognized in earnings	888		930		20,366
BAFC Ser 4 [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Investment [Line Items]
Vintage	2007
Lowest Credit Rating	CCC	[1]
Amortized Cost	14,026
Amount of other-than-temporary impairment recognized in earnings	0		79		63
CWALT Ser 73CB 1 [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Investment [Line Items]
Vintage	2005
Lowest Credit Rating	CC	[1]
Amortized Cost	3,370
Amount of other-than-temporary impairment recognized in earnings	0		207		83
CWALT Ser 73CB 2 [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Investment [Line Items]
Vintage	2005
Lowest Credit Rating	CC	[1]
Amortized Cost	4,477
Amount of other-than-temporary impairment recognized in earnings	0		427		182
CWHL 2006-10 [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Investment [Line Items]
Vintage	2006	[2]
Amount of other-than-temporary impairment recognized in earnings	0	[2]	309	[2]	762	[2]
CWHL 2005-20 [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Investment [Line Items]
Vintage	2005
Lowest Credit Rating	CC	[1]
Amortized Cost	4,191
Amount of other-than-temporary impairment recognized in earnings	0		39		72
FHASI Ser 4 [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Investment [Line Items]
Vintage	2007
Lowest Credit Rating	C	[1]
Amortized Cost	18,933
Amount of other-than-temporary impairment recognized in earnings	340		629		223
HALO Ser 1R [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Investment [Line Items]
Vintage	2006
Lowest Credit Rating	B	[1]
Amortized Cost	15,640
Amount of other-than-temporary impairment recognized in earnings	16		0		0
RFMSI Ser S9 [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Investment [Line Items]
Vintage	2006	[3]
Amount of other-than-temporary impairment recognized in earnings	0	[3]	923	[3]	1,880	[3]
RFMSI Ser S10 [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Investment [Line Items]
Vintage	2006
Lowest Credit Rating	D	[1]
Amortized Cost	3,971
Amount of other-than-temporary impairment recognized in earnings	165		76		249
RALI QS2 [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Investment [Line Items]
Vintage	2006	[3]
Amount of other-than-temporary impairment recognized in earnings	0	[3]	278	[3]	739	[3]
RFMSI S1 [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Investment [Line Items]
Vintage	2006
Lowest Credit Rating	CC	[1]
Amortized Cost	2,299
Amount of other-than-temporary impairment recognized in earnings	0		30		176
TROPC [Member] | Pooled Trust Preferred Securities Group 2 [Member]
Investment [Line Items]
Vintage	2003
Lowest Credit Rating	C	[1]
Amortized Cost	87
Amount of other-than-temporary impairment recognized in earnings	888		444		3,517
MM Community Funding IX [Member] | Pooled Trust Preferred Securities Group 2 [Member]
Investment [Line Items]
Vintage	2003
Lowest Credit Rating	D	[1]
Amortized Cost	2,067
Amount of other-than-temporary impairment recognized in earnings	0		165		2,612
Reg Div Funding 2004 [Member] | Pooled Trust Preferred Securities Group 2 [Member]
Investment [Line Items]
Vintage	2004
Lowest Credit Rating	D	[1]
Amortized Cost	4,177
Amount of other-than-temporary impairment recognized in earnings	0		321		5,199
Pretsl XII [Member] | Pooled Trust Preferred Securities Group 2 [Member]
Investment [Line Items]
Vintage	2003
Lowest Credit Rating	C	[1]
Amortized Cost	2,886
Amount of other-than-temporary impairment recognized in earnings	0		0		1,897
Pretsl XV [Member] | Pooled Trust Preferred Securities Group 2 [Member]
Investment [Line Items]
Vintage	2004
Lowest Credit Rating	C	[1]
Amortized Cost	1,695
Amount of other-than-temporary impairment recognized in earnings	0		0		3,374
Reg Div Funding 2005 [Member] | Pooled Trust Preferred Securities Group 2 [Member]
Investment [Line Items]
Vintage	2005
Lowest Credit Rating	C	[1]
Amortized Cost	311
Amount of other-than-temporary impairment recognized in earnings	0		0		3,767
Life -To Date [Member]
Investment [Line Items]
Total other-than-temporary-impairment recognized in earnings	30,131
Life -To Date [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Investment [Line Items]
Life-to-date	7,947
Life -To Date [Member] | Pooled Trust Preferred Securities Group 2 [Member]
Investment [Line Items]
Life-to-date	22,184
Life -To Date [Member] | BAFC Ser 4 [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Investment [Line Items]
Life-to-date	142
Life -To Date [Member] | CWALT Ser 73CB 1 [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Investment [Line Items]
Life-to-date	290
Life -To Date [Member] | CWALT Ser 73CB 2 [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Investment [Line Items]
Life-to-date	609
Life -To Date [Member] | CWHL 2006-10 [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Investment [Line Items]
Life-to-date	1,071	[2]
Life -To Date [Member] | CWHL 2005-20 [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Investment [Line Items]
Life-to-date	111
Life -To Date [Member] | FHASI Ser 4 [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Investment [Line Items]
Life-to-date	1,192
Life -To Date [Member] | HALO Ser 1R [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Investment [Line Items]
Life-to-date	16
Life -To Date [Member] | RFMSI Ser S9 [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Investment [Line Items]
Life-to-date	2,803	[3]
Life -To Date [Member] | RFMSI Ser S10 [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Investment [Line Items]
Life-to-date	490
Life -To Date [Member] | RALI QS2 [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Investment [Line Items]
Life-to-date	1,017	[3]
Life -To Date [Member] | RFMSI S1 [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Investment [Line Items]
Life-to-date	206
Life -To Date [Member] | TROPC [Member] | Pooled Trust Preferred Securities Group 2 [Member]
Investment [Line Items]
Life-to-date	4,849
Life -To Date [Member] | MM Community Funding IX [Member] | Pooled Trust Preferred Securities Group 2 [Member]
Investment [Line Items]
Life-to-date	2,777
Life -To Date [Member] | Reg Div Funding 2004 [Member] | Pooled Trust Preferred Securities Group 2 [Member]
Investment [Line Items]
Life-to-date	5,520
Life -To Date [Member] | Pretsl XII [Member] | Pooled Trust Preferred Securities Group 2 [Member]
Investment [Line Items]
Life-to-date	1,897
Life -To Date [Member] | Pretsl XV [Member] | Pooled Trust Preferred Securities Group 2 [Member]
Investment [Line Items]
Life-to-date	3,374
Life -To Date [Member] | Reg Div Funding 2005 [Member] | Pooled Trust Preferred Securities Group 2 [Member]
Investment [Line Items]
Life-to-date	$ 3,767

[1] Lowest rating for the security provided by any nationally recognized credit rating agency.

[2] Sold during first quarter 2011.

[3] Sold during fourth quarter 2010.