Held-to-Maturity Securities (Other-Than-Temporary Impairment Analysis) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013 position	Sep. 30, 2012	Sep. 30, 2013 position	Sep. 30, 2012
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Held-to-maturity, Qualitative Disclosure, Non Agency RMBS Number of Positions	30		30
Held-to-maturity, Qualitative Disclosure, Non Agency RMBS Number of Securities, Previously Identified as OTTI	14		14
Other than Temporary Impairment Losses, Investments, Held-to-maturity Securities [Abstract]
Other Than Temporarily Impaired Securities, Unpaid Principal Balance	$ 138,466		$ 138,466
Other Than Temporarily Impaired Securities, Amortized Cost	125,900		125,900
Other Than Temporarily Impaired Securities, Cumulative Non-credit Impairment	94,805		94,805
Other Than Temporarily Impaired Securities, Cumulative Accretion of Non-credit Impairment	59,512		59,512
Other Than Temporarily Impaired Securities, Carrying Value	90,607		90,607
Other Than Temporarily Impaired Securities, Fair Value	112,949		112,949
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Roll Forward]
Balance of Credit Losses Recognized in Earnings, beginning of period	13,039	13,039	13,039	12,679
Other than Temporary Impairment, Credit Losses Recognized in Earnings, Additions, Additional Credit Losses	0	0	0	360
Principal Losses Realized During The Period	(614)	0	(614)	0
Increase In Cash Flows Expected To Be Collected	(70)	0	(70)	0
Balance of Credit Losses Recognized in Earnings, end of period	12,355	13,039	12,355	13,039
Minimum [Member]
Other than Temporary Impairment Losses, Investments, Held-to-maturity Securities, Portion Recognized in Earnings, Net, Qualitative Disclosures [Abstract]
Projected House Price Decline Rate Over the Next 12 Months	5.00%		5.00%
Projected Home Price Recovery, One to Six Months, Percent	0.00%		0.00%
Projected Home Price Recovery, Seven to Twelve Months, Percent	1.00%		1.00%
Projected Home Price Recovery, Thirteen to Eighteen Months, Percent	2.00%		2.00%
Projected Home Price Recovery, Nineteen to Thirty Months, Percent	2.00%		2.00%
Projected Home Price Recovery, Thirty One to Fifty Four Months, Percent	2.00%		2.00%
Projected Home Price Recovery, Months Thereafter, Percent	2.30%		2.30%
Maximum [Member]
Other than Temporary Impairment Losses, Investments, Held-to-maturity Securities, Portion Recognized in Earnings, Net, Qualitative Disclosures [Abstract]
Projected House Price Recovery Rate Over the Next 12 Months	8.00%		8.00%
Projected Home Price Recovery, One to Six Months, Percent	3.00%		3.00%
Projected Home Price Recovery, Seven to Twelve Months, Percent	4.00%		4.00%
Projected Home Price Recovery, Thirteen to Eighteen Months, Percent	4.00%		4.00%
Projected Home Price Recovery, Nineteen to Thirty Months, Percent	5.00%		5.00%
Projected Home Price Recovery, Thirty One to Fifty Four Months, Percent	6.00%		6.00%
Projected Home Price Recovery, Months Thereafter, Percent	5.60%		5.60%
Q1 2009 [Member] | Private Label Residential Mortgage Backed Securities, Security One [Member]
Other than Temporary Impairment Losses, Investments, Held-to-maturity Securities [Abstract]
Debt Instrument, Credit Rating	Triple-C
Other Than Temporarily Impaired Securities, Unpaid Principal Balance	13,288		13,288
Other Than Temporarily Impaired Securities, Amortized Cost	10,438		10,438
Other Than Temporarily Impaired Securities, Cumulative Non-credit Impairment	10,271		10,271
Other Than Temporarily Impaired Securities, Cumulative Accretion of Non-credit Impairment	7,405		7,405
Other Than Temporarily Impaired Securities, Carrying Value	7,572		7,572
Other Than Temporarily Impaired Securities, Fair Value	9,622		9,622
Q1 2009 [Member] | Private Label Residential Mortgage Backed Securities, Security Two [Member]
Other than Temporary Impairment Losses, Investments, Held-to-maturity Securities [Abstract]
Debt Instrument, Credit Rating	Triple-C
Other Than Temporarily Impaired Securities, Unpaid Principal Balance	13,174		13,174
Other Than Temporarily Impaired Securities, Amortized Cost	12,479		12,479
Other Than Temporarily Impaired Securities, Cumulative Non-credit Impairment	12,389		12,389
Other Than Temporarily Impaired Securities, Cumulative Accretion of Non-credit Impairment	7,975		7,975
Other Than Temporarily Impaired Securities, Carrying Value	8,065		8,065
Other Than Temporarily Impaired Securities, Fair Value	10,833		10,833
Q2 2009 [Member] | Private Label Residential Mortgage Backed Securities, Security Three [Member]
Other than Temporary Impairment Losses, Investments, Held-to-maturity Securities [Abstract]
Debt Instrument, Credit Rating	Single-D
Other Than Temporarily Impaired Securities, Unpaid Principal Balance	20,824		20,824
Other Than Temporarily Impaired Securities, Amortized Cost	16,535		16,535
Other Than Temporarily Impaired Securities, Cumulative Non-credit Impairment	15,283		15,283
Other Than Temporarily Impaired Securities, Cumulative Accretion of Non-credit Impairment	10,921		10,921
Other Than Temporarily Impaired Securities, Carrying Value	12,173		12,173
Other Than Temporarily Impaired Securities, Fair Value	16,847		16,847
Q2 2009 [Member] | Private Label Residential Mortgage Backed Securities, Security Four [Member]
Other than Temporary Impairment Losses, Investments, Held-to-maturity Securities [Abstract]
Debt Instrument, Credit Rating	Triple-C
Other Than Temporarily Impaired Securities, Unpaid Principal Balance	9,341		9,341
Other Than Temporarily Impaired Securities, Amortized Cost	8,627		8,627
Other Than Temporarily Impaired Securities, Cumulative Non-credit Impairment	7,890		7,890
Other Than Temporarily Impaired Securities, Cumulative Accretion of Non-credit Impairment	5,288		5,288
Other Than Temporarily Impaired Securities, Carrying Value	6,025		6,025
Other Than Temporarily Impaired Securities, Fair Value	7,910		7,910
Q3 2009 [Member] | Private Label Residential Mortgage Backed Securities, Security Five [Member]
Other than Temporary Impairment Losses, Investments, Held-to-maturity Securities [Abstract]
Debt Instrument, Credit Rating	Triple-C
Other Than Temporarily Impaired Securities, Unpaid Principal Balance	16,289		16,289
Other Than Temporarily Impaired Securities, Amortized Cost	14,569		14,569
Other Than Temporarily Impaired Securities, Cumulative Non-credit Impairment	10,047		10,047
Other Than Temporarily Impaired Securities, Cumulative Accretion of Non-credit Impairment	6,800		6,800
Other Than Temporarily Impaired Securities, Carrying Value	11,322		11,322
Other Than Temporarily Impaired Securities, Fair Value	13,201		13,201
Q3 2009 [Member] | Private Label Residential Mortgage Backed Securities, Security Six [Member]
Other than Temporary Impairment Losses, Investments, Held-to-maturity Securities [Abstract]
Debt Instrument, Credit Rating	Triple-C
Other Than Temporarily Impaired Securities, Unpaid Principal Balance	14,271		14,271
Other Than Temporarily Impaired Securities, Amortized Cost	12,870		12,870
Other Than Temporarily Impaired Securities, Cumulative Non-credit Impairment	10,567		10,567
Other Than Temporarily Impaired Securities, Cumulative Accretion of Non-credit Impairment	6,567		6,567
Other Than Temporarily Impaired Securities, Carrying Value	8,870		8,870
Other Than Temporarily Impaired Securities, Fair Value	11,257		11,257
Q3 2009 [Member] | Private Label Residential Mortgage Backed Securities, Security Seven [Member]
Other than Temporary Impairment Losses, Investments, Held-to-maturity Securities [Abstract]
Debt Instrument, Credit Rating	Single-B
Other Than Temporarily Impaired Securities, Unpaid Principal Balance	5,093		5,093
Other Than Temporarily Impaired Securities, Amortized Cost	5,015		5,015
Other Than Temporarily Impaired Securities, Cumulative Non-credit Impairment	3,575		3,575
Other Than Temporarily Impaired Securities, Cumulative Accretion of Non-credit Impairment	2,130		2,130
Other Than Temporarily Impaired Securities, Carrying Value	3,570		3,570
Other Than Temporarily Impaired Securities, Fair Value	4,546		4,546
Q1 2010 [Member] | Private Label Residential Mortgage Backed Securities, Security Eight [Member]
Other than Temporary Impairment Losses, Investments, Held-to-maturity Securities [Abstract]
Debt Instrument, Credit Rating	Triple-C
Other Than Temporarily Impaired Securities, Unpaid Principal Balance	7,641		7,641
Other Than Temporarily Impaired Securities, Amortized Cost	7,619		7,619
Other Than Temporarily Impaired Securities, Cumulative Non-credit Impairment	4,968		4,968
Other Than Temporarily Impaired Securities, Cumulative Accretion of Non-credit Impairment	2,840		2,840
Other Than Temporarily Impaired Securities, Carrying Value	5,491		5,491
Other Than Temporarily Impaired Securities, Fair Value	6,645		6,645
Q1 2010 [Member] | Private Label Residential Mortgage Backed Securities, Security Nine [Member]
Other than Temporary Impairment Losses, Investments, Held-to-maturity Securities [Abstract]
Debt Instrument, Credit Rating	Triple-C
Other Than Temporarily Impaired Securities, Unpaid Principal Balance	3,182		3,182
Other Than Temporarily Impaired Securities, Amortized Cost	3,145		3,145
Other Than Temporarily Impaired Securities, Cumulative Non-credit Impairment	2,208		2,208
Other Than Temporarily Impaired Securities, Cumulative Accretion of Non-credit Impairment	1,257		1,257
Other Than Temporarily Impaired Securities, Carrying Value	2,194		2,194
Other Than Temporarily Impaired Securities, Fair Value	2,672		2,672
Q4 2010 [Member] | Private Label Residential Mortgage Backed Securities, Security Ten [Member]
Other than Temporary Impairment Losses, Investments, Held-to-maturity Securities [Abstract]
Debt Instrument, Credit Rating	Triple-C
Other Than Temporarily Impaired Securities, Unpaid Principal Balance	6,309		6,309
Other Than Temporarily Impaired Securities, Amortized Cost	5,884		5,884
Other Than Temporarily Impaired Securities, Cumulative Non-credit Impairment	3,331		3,331
Other Than Temporarily Impaired Securities, Cumulative Accretion of Non-credit Impairment	1,479		1,479
Other Than Temporarily Impaired Securities, Carrying Value	4,032		4,032
Other Than Temporarily Impaired Securities, Fair Value	5,110		5,110
Q4 2010 [Member] | Private Label Residential Mortgage Backed Securities, Security Eleven [Member]
Other than Temporary Impairment Losses, Investments, Held-to-maturity Securities [Abstract]
Debt Instrument, Credit Rating	Triple-C
Other Than Temporarily Impaired Securities, Unpaid Principal Balance	7,745		7,745
Other Than Temporarily Impaired Securities, Amortized Cost	7,740		7,740
Other Than Temporarily Impaired Securities, Cumulative Non-credit Impairment	4,096		4,096
Other Than Temporarily Impaired Securities, Cumulative Accretion of Non-credit Impairment	1,870		1,870
Other Than Temporarily Impaired Securities, Carrying Value	5,514		5,514
Other Than Temporarily Impaired Securities, Fair Value	6,435		6,435
Q4 2010 [Member] | Private Label Residential Mortgage Backed Securities, Security Twelve [Member]
Other than Temporary Impairment Losses, Investments, Held-to-maturity Securities [Abstract]
Debt Instrument, Credit Rating	Triple-C
Other Than Temporarily Impaired Securities, Unpaid Principal Balance	4,145		4,145
Other Than Temporarily Impaired Securities, Amortized Cost	4,061		4,061
Other Than Temporarily Impaired Securities, Cumulative Non-credit Impairment	1,820		1,820
Other Than Temporarily Impaired Securities, Cumulative Accretion of Non-credit Impairment	815		815
Other Than Temporarily Impaired Securities, Carrying Value	3,056		3,056
Other Than Temporarily Impaired Securities, Fair Value	3,466		3,466
Q4 2010 [Member] | Private Label Residential Mortgage Backed Securities, Security Thirteen [Member]
Other than Temporary Impairment Losses, Investments, Held-to-maturity Securities [Abstract]
Debt Instrument, Credit Rating	Triple-C
Other Than Temporarily Impaired Securities, Unpaid Principal Balance	4,938		4,938
Other Than Temporarily Impaired Securities, Amortized Cost	4,923		4,923
Other Than Temporarily Impaired Securities, Cumulative Non-credit Impairment	2,418		2,418
Other Than Temporarily Impaired Securities, Cumulative Accretion of Non-credit Impairment	1,216		1,216
Other Than Temporarily Impaired Securities, Carrying Value	3,721		3,721
Other Than Temporarily Impaired Securities, Fair Value	4,224		4,224
Q2 2011 [Member] | Private Label Residential Mortgage Backed Securities, Security Fourteen [Member]
Other than Temporary Impairment Losses, Investments, Held-to-maturity Securities [Abstract]
Debt Instrument, Credit Rating	Triple-C
Other Than Temporarily Impaired Securities, Unpaid Principal Balance	12,226		12,226
Other Than Temporarily Impaired Securities, Amortized Cost	11,995		11,995
Other Than Temporarily Impaired Securities, Cumulative Non-credit Impairment	5,942		5,942
Other Than Temporarily Impaired Securities, Cumulative Accretion of Non-credit Impairment	2,949		2,949
Other Than Temporarily Impaired Securities, Carrying Value	9,002		9,002
Other Than Temporarily Impaired Securities, Fair Value	$ 10,181		$ 10,181
Majority of Markets [Member] | Minimum [Member]
Other than Temporary Impairment Losses, Investments, Held-to-maturity Securities, Portion Recognized in Earnings, Net, Qualitative Disclosures [Abstract]
Projected House Price Decline Rate Over the Next 12 Months	3.00%		3.00%
Majority of Markets [Member] | Maximum [Member]
Other than Temporary Impairment Losses, Investments, Held-to-maturity Securities, Portion Recognized in Earnings, Net, Qualitative Disclosures [Abstract]
Projected House Price Recovery Rate Over the Next 12 Months	7.00%		7.00%