Investment Securities (Securities With Other-Than-Temporary Impairment, Cumulative Other-Than-Temporary Impairment) (Details) (USD $) In Thousands	3 Months Ended			9 Months Ended			12 Months Ended
	Sep. 30, 2011		Sep. 30, 2010	Sep. 30, 2011		Sep. 30, 2010	Dec. 31, 2010		Dec. 31, 2009
Amortized Cost	$ 2,205,285			$ 2,205,285			$ 1,953,842
Amount of other-than-temporary impairment recognized in earnings	140		39	1,872		4,441
Total other-than-temporary-impairment recognized in earnings	0		39	499		3,308	3,927		24,795
MM Community Funding IX [Member] | Life To Date [Member] | Pooled Trust Preferred Securities Group 2 [Member]
Life-to-date				2,777
Reg Div Funding 2004 [Member] | Life To Date [Member] | Pooled Trust Preferred Securities Group 2 [Member]
Life-to-date				5,520
Pretsl XII [Member] | Life To Date [Member] | Pooled Trust Preferred Securities Group 2 [Member]
Life-to-date				1,897
Pretsl XV [Member] | Life To Date [Member] | Pooled Trust Preferred Securities Group 2 [Member]
Life-to-date				3,374
Reg Div Funding 2005 [Member] | Life To Date [Member] | Pooled Trust Preferred Securities Group 2 [Member]
Life-to-date				3,767
Life To Date [Member]
Total other-than-temporary-impairment recognized in earnings				29,221
Life To Date [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Life-to-date				7,925
Life To Date [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member] | BAFC Ser 4 [Member]
Life-to-date				142
Life To Date [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member] | CWALT Ser 73CB 1 [Member]
Life-to-date				290
Life To Date [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member] | CWALT Ser 73CB 2 [Member]
Life-to-date				609
Life To Date [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member] | CWHL 2006-10 [Member]
Life-to-date				1,071	[1]
Life To Date [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member] | CWHL 2005-20 [Member]
Life-to-date				111
Life To Date [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member] | FHASI Ser 4 [Member]
Life-to-date				1,192
Life To Date [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member] | HALO Ser 1R [Member]
Life-to-date				16
Life To Date [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member] | RFMSI Ser S9 [Member]
Life-to-date				2,803	[2]
Life To Date [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member] | RFMSI Ser S10 [Member]
Life-to-date				468
Life To Date [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member] | RALI QS2 [Member]
Life-to-date				1,017	[2]
Life To Date [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member] | RFMSI S1 [Member]
Life-to-date				206
Life To Date [Member] | Pooled Trust Preferred Securities Group 2 [Member]
Life-to-date				21,296
Life To Date [Member] | Pooled Trust Preferred Securities Group 2 [Member] | TROPC [Member]
Life-to-date				3,961
Mortgage-Backed Securities - Non-Agency Group 2 [Member] | BAFC Ser 4 [Member]
Vintage				2007
Lowest Credit Rating	CCC	[3]		CCC	[3]
Amortized Cost	14,026			14,026
Amount of other-than-temporary impairment recognized in earnings				0			79		63
Mortgage-Backed Securities - Non-Agency Group 2 [Member] | CWALT Ser 73CB 1 [Member]
Vintage				2005
Lowest Credit Rating	CC	[3]		CC	[3]
Amortized Cost	3,842			3,842
Amount of other-than-temporary impairment recognized in earnings				0			207		83
Mortgage-Backed Securities - Non-Agency Group 2 [Member] | CWALT Ser 73CB 2 [Member]
Vintage				2005
Lowest Credit Rating	CC	[3]		CC	[3]
Amortized Cost	4,791			4,791
Amount of other-than-temporary impairment recognized in earnings				0			427		182
Mortgage-Backed Securities - Non-Agency Group 2 [Member] | CWHL 2006-10 [Member]
Vintage				2006	[1]
Amount of other-than-temporary impairment recognized in earnings				0	[1]		309	[1]	762	[1]
Mortgage-Backed Securities - Non-Agency Group 2 [Member] | CWHL 2005-20 [Member]
Vintage				2005
Lowest Credit Rating	CC	[3]		CC	[3]
Amortized Cost	5,332			5,332
Amount of other-than-temporary impairment recognized in earnings				0			39		72
Mortgage-Backed Securities - Non-Agency Group 2 [Member] | FHASI Ser 4 [Member]
Vintage				2007
Lowest Credit Rating	CC	[3]		CC	[3]
Amortized Cost	20,003			20,003
Amount of other-than-temporary impairment recognized in earnings				340			629		223
Mortgage-Backed Securities - Non-Agency Group 2 [Member] | HALO Ser 1R [Member]
Vintage				2006
Lowest Credit Rating	B	[3]		B	[3]
Amortized Cost	15,640			15,640
Amount of other-than-temporary impairment recognized in earnings				16			0		0
Mortgage-Backed Securities - Non-Agency Group 2 [Member] | RFMSI Ser S9 [Member]
Vintage				2006	[2]
Amount of other-than-temporary impairment recognized in earnings				0	[2]		923	[2]	1,880	[2]
Mortgage-Backed Securities - Non-Agency Group 2 [Member] | RFMSI Ser S10 [Member]
Vintage				2006
Lowest Credit Rating	CC	[3]		CC	[3]
Amortized Cost	4,217			4,217
Amount of other-than-temporary impairment recognized in earnings				143			76		249
Mortgage-Backed Securities - Non-Agency Group 2 [Member] | RALI QS2 [Member]
Vintage				2006	[2]
Amount of other-than-temporary impairment recognized in earnings				0	[2]		278	[2]	739	[2]
Mortgage-Backed Securities - Non-Agency Group 2 [Member] | RFMSI S1 [Member]
Vintage				2006
Lowest Credit Rating	CCC	[3]		CCC	[3]
Amortized Cost	2,802			2,802
Amount of other-than-temporary impairment recognized in earnings				0			30		176
Pooled Trust Preferred Securities Group 2 [Member] | TROPC [Member]
Vintage				2003
Lowest Credit Rating	C	[3]		C	[3]
Amortized Cost	977			977
Amount of other-than-temporary impairment recognized in earnings				0			444		3,517
MM Community Funding IX [Member] | Pooled Trust Preferred Securities Group 2 [Member]
Vintage				2003
Lowest Credit Rating	D	[3]		D	[3]
Amortized Cost	2,076			2,076
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]
Vintage				2004
Lowest Credit Rating	D	[3]		D	[3]
Amortized Cost	4,194			4,194
Amount of other-than-temporary impairment recognized in earnings				0			321		5,199
Pretsl XII [Member] | Pooled Trust Preferred Securities Group 2 [Member]
Vintage				2003
Lowest Credit Rating	C	[3]		C	[3]
Amortized Cost	2,886			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]
Vintage				2004
Lowest Credit Rating	C	[3]		C	[3]
Amortized Cost	1,695			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]
Vintage				2005
Lowest Credit Rating	C	[3]		C	[3]
Amortized Cost	311			311
Amount of other-than-temporary impairment recognized in earnings				0			0		3,767
Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Amortized Cost	70,653			70,653
Amount of other-than-temporary impairment recognized in earnings				499			2,997		4,429
Total other-than-temporary-impairment recognized in earnings	0			499
Pooled Trust Preferred Securities Group 2 [Member]
Amortized Cost	12,139			12,139
Amount of other-than-temporary impairment recognized in earnings				$ 0			$ 930		$ 20,366

[1] Sold during first quarter 2011.

[2] Sold during fourth quarter 2010.

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