Investment Securities (Securities With Other-Than-Temporary-Impairment, Cumulative Other-Than-Temporary-Impairment) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended			6 Months Ended			12 Months Ended
	Jun. 30, 2012		Jun. 30, 2011	Jun. 30, 2012		Jun. 30, 2011	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Amortized Cost	$ 2,155,885			$ 2,155,885			$ 2,030,801
Amount of other-than-temporary-impairment recognized in earnings	780		1,433	876		1,732
Total other-than-temporary-impairment recognized in earnings	780		200	876		499	1,409		3,927		24,795
Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Amortized Cost	67,355			67,355
Amount of other-than-temporary-impairment recognized in earnings				715			521		2,997		4,429
Pooled Trust Preferred Securities Group 2 [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Amortized Cost	11,019			11,019
Amount of other-than-temporary-impairment recognized in earnings				161			888		930		20,366
BAFC Ser 4 [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Debt Issuance Year	2007
Lowest Credit Rating	CCC	[1]		CCC	[1]
Amortized Cost	13,176			13,176
Amount of other-than-temporary-impairment recognized in earnings				160			0		79		63
CWALT Ser 73CB 1 [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Debt Issuance Year	2005
Lowest Credit Rating	D	[1]		D	[1]
Amortized Cost	2,772			2,772
Amount of other-than-temporary-impairment recognized in earnings				117			0		207		83
CWALT Ser 73CB 2 [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Debt Issuance Year	2005	[2]
Lowest Credit Rating	D	[1],[2]		D	[1],[2]
Amortized Cost	3,980	[2]		3,980	[2]
Amount of other-than-temporary-impairment recognized in earnings				0	[2]		0	[2]	427	[2]	182	[2]
CWHL 2006-10 [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Debt Issuance Year	2006	[2]
Amount of other-than-temporary-impairment recognized in earnings				0	[2]		0	[2]	309	[2]	762	[2]
CWHL 2005-20 [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Debt Issuance Year	2005
Lowest Credit Rating	CC	[1]		CC	[1]
Amortized Cost	2,168			2,168
Amount of other-than-temporary-impairment recognized in earnings				0			0		39		72
FHASI Ser 4 [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Debt Issuance Year	2007
Lowest Credit Rating	C	[1]		C	[1]
Amortized Cost	16,803			16,803
Amount of other-than-temporary-impairment recognized in earnings				0			340		629		223
HALO Ser 1R [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Debt Issuance Year	2006
Lowest Credit Rating	B	[1]		B	[1]
Amortized Cost	15,470			15,470
Amount of other-than-temporary-impairment recognized in earnings				133			16		0		0
RFMSI Ser S9 [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Debt Issuance Year	2006	[3]
Amount of other-than-temporary-impairment recognized in earnings				0	[3]		0	[3]	923	[3]	1,880	[3]
RFMSI Ser S10 [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Debt Issuance Year	2006
Lowest Credit Rating	D	[1]		D	[1]
Amortized Cost	3,419			3,419
Amount of other-than-temporary-impairment recognized in earnings				163			165		76		249
RALI QS2 [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Debt Issuance Year	2006	[3]
Amount of other-than-temporary-impairment recognized in earnings				0	[3]		0	[3]	278	[3]	739	[3]
RAST A9 [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Debt Issuance Year	2004
Lowest Credit Rating	CCC	[1]		CCC	[1]
Amortized Cost	9,567			9,567
Amount of other-than-temporary-impairment recognized in earnings				142			0		0		0
RFMSI S1 [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Debt Issuance Year	2006	[4]
Amount of other-than-temporary-impairment recognized in earnings				0	[4]		0	[4]	30	[4]	176	[4]
TROPC [Member] | Pooled Trust Preferred Securities Group 2 [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Debt Issuance Year	2003
Lowest Credit Rating	C	[1]		C	[1]
Amortized Cost	86			86
Amount of other-than-temporary-impairment recognized in earnings				0			888		444		3,517
MM Community Funding IX [Member] | Pooled Trust Preferred Securities Group 2 [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Debt Issuance Year	2003
Lowest Credit Rating	D	[1]		D	[1]
Amortized Cost	2,067			2,067
Amount of other-than-temporary-impairment recognized in earnings				0			0		165		2,612
Reg Div Funding 2004 [Member] | Pooled Trust Preferred Securities Group 2 [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Debt Issuance Year	2004
Lowest Credit Rating	D	[1]		D	[1]
Amortized Cost	4,017			4,017
Amount of other-than-temporary-impairment recognized in earnings				161			0		321		5,199
Pretsl XII [Member] | Pooled Trust Preferred Securities Group 2 [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Debt Issuance Year	2003
Lowest Credit Rating	C	[1]		C	[1]
Amortized Cost	2,843			2,843
Amount of other-than-temporary-impairment recognized in earnings				0			0		0		1,897
Pretsl XV [Member] | Pooled Trust Preferred Securities Group 2 [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Debt Issuance Year	2004
Lowest Credit Rating	C	[1]		C	[1]
Amortized Cost	1,695			1,695
Amount of other-than-temporary-impairment recognized in earnings				0			0		0		3,374
Reg Div Funding 2005 [Member] | Pooled Trust Preferred Securities Group 2 [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Debt Issuance Year	2005
Lowest Credit Rating	C	[1]		C	[1]
Amortized Cost	311			311
Amount of other-than-temporary-impairment recognized in earnings				0			0		0		3,767
Life To Date [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Total other-than-temporary-impairment recognized in earnings				31,007
Life To Date [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Life-to-date				8,662
Life To Date [Member] | Pooled Trust Preferred Securities Group 2 [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Life-to-date				22,345
Life To Date [Member] | BAFC Ser 4 [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Life-to-date				302
Life To Date [Member] | CWALT Ser 73CB 1 [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Life-to-date				407
Life To Date [Member] | CWALT Ser 73CB 2 [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Life-to-date				609	[2]
Life To Date [Member] | CWHL 2006-10 [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Life-to-date				1,071	[2]
Life To Date [Member] | CWHL 2005-20 [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Life-to-date				111
Life To Date [Member] | FHASI Ser 4 [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Life-to-date				1,192
Life To Date [Member] | HALO Ser 1R [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Life-to-date				149
Life To Date [Member] | RFMSI Ser S9 [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Life-to-date				2,803	[3]
Life To Date [Member] | RFMSI Ser S10 [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Life-to-date				653
Life To Date [Member] | RALI QS2 [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Life-to-date				1,017	[3]
Life To Date [Member] | RAST A9 [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Life-to-date				142
Life To Date [Member] | RFMSI S1 [Member] | Mortgage-Backed Securities - Non-Agency Group 2 [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Life-to-date				206	[4]
Life To Date [Member] | TROPC [Member] | Pooled Trust Preferred Securities Group 2 [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Life-to-date				4,849
Life To Date [Member] | MM Community Funding IX [Member] | Pooled Trust Preferred Securities Group 2 [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Life-to-date				2,777
Life To Date [Member] | Reg Div Funding 2004 [Member] | Pooled Trust Preferred Securities Group 2 [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Life-to-date				5,681
Life To Date [Member] | Pretsl XII [Member] | Pooled Trust Preferred Securities Group 2 [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Life-to-date				1,897
Life To Date [Member] | Pretsl XV [Member] | Pooled Trust Preferred Securities Group 2 [Member]
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Life-to-date				3,374
Life To Date [Member] | Reg Div Funding 2005 [Member] | Pooled Trust Preferred Securities Group 2 [Member]
Schedule Of Available For Sale And Held To Maturity Securities [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.

[4] Sold during second quarter 2012.