Available for Sale Securities (Details) (USD $)	12 Months Ended					48 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	$ 11,032,634,000		$ 9,957,205,000			$ 11,032,634,000
Available-for-sale Securities, Fair Value	11,287,221,000		10,179,365,000			11,287,221,000
Available-for-sale Securities, Gross Unrealized Gains	261,184,000	[1]	308,297,000	[1]		261,184,000	[1]
Available-for-sale Securities, Gross Unrealized Losses	2,414,000	[1]	13,331,000	[1]		2,414,000	[1]
Available-for-Sale Securities, Other Than Temporary Impairments	4,183,000	[2]	72,806,000	[2]		4,183,000	[2]
Available-for-sale Securities, Debt Maturities, Nominal Yield [Abstract]
Available-for-sale Securities, Debt Maturities, Nominal Yield	2.19%					2.19%
Available-for-sale Securities, Pledged as Collateral [Abstract]
Available-for-sale Securities, Pledged As Collateral, Amortized Cost	4,070,250,000		4,188,075,000			4,070,250,000
Available-for-sale Securities, Pledged As Collateral, Fair Value	4,186,390,000		4,334,553,000			4,186,390,000
Available-for-sale Securities, Gross Realized Gain (Loss), Disclosures [Abstract]
Available-for-sale Securities, Gross Realized Gains (Losses), Sale Proceeds	1,744,662,000		2,725,760,000		2,013,620,000
Available-for-sale Securities, Gross Realized Gains	41,191,000		41,284,000		26,007,000
Available-for-sale Securities, Gross Realized Losses	(7,346,000)		(7,140,000)		(4,125,000)
Other Comprehensive Income (Loss), Reclassification Adjustment for Sale of Securities Included in Net Income, Tax	13,166,000		13,282,000		8,512,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	106		109			106
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	448,144,000		95,247,000			448,144,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	159,428,000		435,233,000			159,428,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	607,572,000		530,480,000			607,572,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	1,850,000		2,616,000			1,850,000
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	4,747,000		83,521,000			4,747,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	6,597,000		86,137,000			6,597,000
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities, Portion Recognized In Earnings, Net Qualitative Disclosures, Lowest Current Credit Rating [Abstract]
Available-for-sale Securities, Portfolio Concentration US Govt or GSE Securities Not Rated, Amortized Cost	10,542,396,000	[3]				10,542,396,000	[3]
Available-for-sale Securities, Portfolio Concentration US Govt or GSE Securities Not Rated, Fair Value	10,785,898,000	[3]				10,785,898,000	[3]
Available-for-sale securities, Portfolio Concentration Rated AAA To AA, Amortized Cost	65,076,000					65,076,000
Available-for-sale Securities, Portfolio Concentration Rated AAA To AA, Fair Value	67,142,000					67,142,000
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Amortized Cost	63,855,000					63,855,000
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Fair Value	67,558,000					67,558,000
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Amortized Cost	335,286,000					335,286,000
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value	337,547,000					337,547,000
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Net Unrealized Gain (Loss)	2,300,000					2,300,000
Available-for-sale Securities, Portfolio Concentration Not Rated, Amortized Cost	26,021,000					26,021,000
Available-for-sale Securities, Portfolio Concentration Not Rated, Fair Value	29,076,000					29,076,000
Other Than Temporary Impairment Losses, Investments, Available-for-sale Securities, Portion Recognized in Earnings, Net, Qualitative Disclosures, Assumptions Used to Develop Projected Cash Flows [Abstract]
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities, Qualitative Disclosures, Projected Housing Price Depreciation, Months 13-24	0.00%		2.00%			0.00%
Fixed Maturity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	121,572,000					121,572,000
Available-for-sale Securities, Fair Value	124,533,000					124,533,000
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Next Rolling Twelve Months, Amortized Cost Basis	1,794,000					1,794,000
Available-for-sale Securities, Debt Maturities, Rolling Year Two Through Five, Amortized Cost Basis	59,878,000					59,878,000
Available-for-sale Securities, Debt Maturities, Rolling Year Six Through Ten, Amortized Cost Basis	11,121,000					11,121,000
Available-for-sale Securities, Debt Maturities, Rolling after Year Ten, Amortized Cost Basis	48,779,000					48,779,000
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Next Rolling Twelve Months, Fair Value	1,814,000					1,814,000
Available-for-sale Securities, Debt Maturities, Rolling Year Two Through Five, Fair Value	61,997,000					61,997,000
Available-for-sale Securities, Debt Maturities, Rolling Year Six Through Ten, Fair Value	11,861,000					11,861,000
Available-for-sale Securities, Debt Maturities, Rolling after Year Ten, Fair Value	48,861,000					48,861,000
Available-for-sale Securities, Debt Maturities, Nominal Yield [Abstract]
Available-for-sale Securities, Debt Maturities, Next Rolling Twelve Months, Nominal Yield	0.31%					0.31%
Available-for-sale Securities, Debt Maturities, Rolling Year Two Through Five, Nominal Yield	1.38%					1.38%
Available-for-sale Securities, Debt Maturities, Rolling Year Six Through Ten, Nominal Yield	0.78%					0.78%
Available-for-sale Securities, Debt Maturities, Rolling after Year Ten, Nominal Yield	2.68%	[4]				2.68%	[4]
Available-for-sale Securities, Debt Maturities, Nominal Yield	1.83%					1.83%
Available-for-sale Securities, Debt Maturities, Weighted Average Maturity	12.09	[5]				12.09	[5]
US Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	1,000,000		1,001,000			1,000,000
Available-for-sale Securities, Fair Value	1,002,000		1,006,000			1,002,000
Available-for-sale Securities, Gross Unrealized Gains	2,000	[1]	5,000	[1]		2,000	[1]
Available-for-sale Securities, Gross Unrealized Losses	0	[1]	0	[1]		0	[1]
Available-for-Sale Securities, Other Than Temporary Impairments	0	[2]	0	[2]		0	[2]
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Next Rolling Twelve Months, Amortized Cost Basis	1,000,000					1,000,000
Available-for-sale Securities, Debt Maturities, Rolling Year Two Through Five, Amortized Cost Basis	0					0
Available-for-sale Securities, Debt Maturities, Rolling Year Six Through Ten, Amortized Cost Basis	0					0
Available-for-sale Securities, Debt Maturities, Rolling after Year Ten, Amortized Cost Basis	0					0
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Next Rolling Twelve Months, Fair Value	1,002,000					1,002,000
Available-for-sale Securities, Debt Maturities, Rolling Year Two Through Five, Fair Value	0					0
Available-for-sale Securities, Debt Maturities, Rolling Year Six Through Ten, Fair Value	0					0
Available-for-sale Securities, Debt Maturities, Rolling after Year Ten, Fair Value	0					0
Available-for-sale Securities, Debt Maturities, Nominal Yield [Abstract]
Available-for-sale Securities, Debt Maturities, Next Rolling Twelve Months, Nominal Yield	0.55%					0.55%
Available-for-sale Securities, Debt Maturities, Rolling Year Two Through Five, Nominal Yield	0.00%					0.00%
Available-for-sale Securities, Debt Maturities, Rolling Year Six Through Ten, Nominal Yield	0.00%					0.00%
Available-for-sale Securities, Debt Maturities, Rolling after Year Ten, Nominal Yield	0.00%	[4]				0.00%	[4]
Available-for-sale Securities, Debt Maturities, Nominal Yield	0.55%					0.55%
Available-for-sale Securities, Debt Maturities, Weighted Average Maturity	0.34	[5]				0.34	[5]
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities, Portion Recognized In Earnings, Net Qualitative Disclosures, Lowest Current Credit Rating [Abstract]
Available-for-sale Securities, Portfolio Concentration US Govt or GSE Securities Not Rated, Amortized Cost	1,000,000	[3]				1,000,000	[3]
Available-for-sale Securities, Portfolio Concentration US Govt or GSE Securities Not Rated, Fair Value	1,002,000	[3]				1,002,000	[3]
Available-for-sale securities, Portfolio Concentration Rated AAA To AA, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Rated AAA To AA, Fair Value	0					0
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Fair Value	0					0
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value	0					0
Available-for-sale Securities, Portfolio Concentration Not Rated, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Not Rated, Fair Value	0					0
Municipal and Other Tax-exempt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	84,892,000		66,435,000			84,892,000
Available-for-sale Securities, Fair Value	87,142,000		68,837,000			87,142,000
Available-for-sale Securities, Gross Unrealized Gains	2,414,000	[1]	2,543,000	[1]		2,414,000	[1]
Available-for-sale Securities, Gross Unrealized Losses	(164,000)	[1]	(141,000)	[1]		(164,000)	[1]
Available-for-Sale Securities, Other Than Temporary Impairments	0	[2]	0	[2]		0	[2]
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Next Rolling Twelve Months, Amortized Cost Basis	794,000					794,000
Available-for-sale Securities, Debt Maturities, Rolling Year Two Through Five, Amortized Cost Basis	29,598,000					29,598,000
Available-for-sale Securities, Debt Maturities, Rolling Year Six Through Ten, Amortized Cost Basis	11,121,000					11,121,000
Available-for-sale Securities, Debt Maturities, Rolling after Year Ten, Amortized Cost Basis	43,379,000					43,379,000
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Next Rolling Twelve Months, Fair Value	812,000					812,000
Available-for-sale Securities, Debt Maturities, Rolling Year Two Through Five, Fair Value	31,007,000					31,007,000
Available-for-sale Securities, Debt Maturities, Rolling Year Six Through Ten, Fair Value	11,861,000					11,861,000
Available-for-sale Securities, Debt Maturities, Rolling after Year Ten, Fair Value	43,462,000					43,462,000
Available-for-sale Securities, Debt Maturities, Nominal Yield [Abstract]
Available-for-sale Securities, Debt Maturities, Next Rolling Twelve Months, Nominal Yield	0.00%	[6]				0.00%	[6]
Available-for-sale Securities, Debt Maturities, Rolling Year Two Through Five, Nominal Yield	0.95%	[6]				0.95%	[6]
Available-for-sale Securities, Debt Maturities, Rolling Year Six Through Ten, Nominal Yield	0.78%	[6]				0.78%	[6]
Available-for-sale Securities, Debt Maturities, Rolling after Year Ten, Nominal Yield	2.85%	[4],[6]				2.85%	[4],[6]
Available-for-sale Securities, Debt Maturities, Nominal Yield	1.89%	[6]				1.89%	[6]
Available-for-sale Securities, Debt Maturities, Weighted Average Maturity	14.59	[5]				14.59	[5]
Available-for-sale Securities, Debt Maturities, Effective tax rate for nominal yield calculation	39.00%					39.00%
Available-for-sale Securities, Debt Maturities, Number of days for interest rates to reset	35 days					35 days
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	38		26			38
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	6,150,000		5,008,000			6,150,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	26,108,000		21,659,000			26,108,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	32,258,000		26,667,000			32,258,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	11,000		7,000			11,000
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	153,000		134,000			153,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	164,000		141,000			164,000
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities, Portion Recognized In Earnings, Net Qualitative Disclosures, Lowest Current Credit Rating [Abstract]
Available-for-sale Securities, Portfolio Concentration US Govt or GSE Securities Not Rated, Amortized Cost	0	[3]				0	[3]
Available-for-sale Securities, Portfolio Concentration US Govt or GSE Securities Not Rated, Fair Value	0	[3]				0	[3]
Available-for-sale securities, Portfolio Concentration Rated AAA To AA, Amortized Cost	59,676,000					59,676,000
Available-for-sale Securities, Portfolio Concentration Rated AAA To AA, Fair Value	61,743,000					61,743,000
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Amortized Cost	11,404,000					11,404,000
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Fair Value	11,496,000					11,496,000
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Amortized Cost	12,384,000					12,384,000
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value	12,384,000					12,384,000
Available-for-sale Securities, Portfolio Concentration Not Rated, Amortized Cost	1,428,000					1,428,000
Available-for-sale Securities, Portfolio Concentration Not Rated, Fair Value	1,519,000					1,519,000
Available-for-sale Securities, Privately Issued Residential Mortgage-backed Securities, Credit losses Recognized [Abstract]
Amount of Credit Losses Recognized in Current Period	(1,000,000)		(1,600,000)		(1,000,000)
Other Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	35,680,000		36,298,000			35,680,000
Available-for-sale Securities, Fair Value	36,389,000		36,495,000			36,389,000
Available-for-sale Securities, Gross Unrealized Gains	709,000	[1]	197,000	[1]		709,000	[1]
Available-for-sale Securities, Gross Unrealized Losses	0	[1]	0	[1]		0	[1]
Available-for-Sale Securities, Other Than Temporary Impairments	0	[2]	0	[2]		0	[2]
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Next Rolling Twelve Months, Amortized Cost Basis	0					0
Available-for-sale Securities, Debt Maturities, Rolling Year Two Through Five, Amortized Cost Basis	30,280,000					30,280,000
Available-for-sale Securities, Debt Maturities, Rolling Year Six Through Ten, Amortized Cost Basis	0					0
Available-for-sale Securities, Debt Maturities, Rolling after Year Ten, Amortized Cost Basis	5,400,000					5,400,000
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Next Rolling Twelve Months, Fair Value	0					0
Available-for-sale Securities, Debt Maturities, Rolling Year Two Through Five, Fair Value	30,990,000					30,990,000
Available-for-sale Securities, Debt Maturities, Rolling Year Six Through Ten, Fair Value	0					0
Available-for-sale Securities, Debt Maturities, Rolling after Year Ten, Fair Value	5,399,000					5,399,000
Available-for-sale Securities, Debt Maturities, Nominal Yield [Abstract]
Available-for-sale Securities, Debt Maturities, Next Rolling Twelve Months, Nominal Yield	0.00%					0.00%
Available-for-sale Securities, Debt Maturities, Rolling Year Two Through Five, Nominal Yield	1.80%					1.80%
Available-for-sale Securities, Debt Maturities, Rolling Year Six Through Ten, Nominal Yield	0.00%					0.00%
Available-for-sale Securities, Debt Maturities, Rolling after Year Ten, Nominal Yield	1.29%	[4]				1.29%	[4]
Available-for-sale Securities, Debt Maturities, Nominal Yield	1.74%					1.74%
Available-for-sale Securities, Debt Maturities, Weighted Average Maturity	6.47	[5]				6.47	[5]
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	3					3
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	4,899,000					4,899,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0					0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	4,899,000					4,899,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	0					0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	0					0
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	0					0
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities, Portion Recognized In Earnings, Net Qualitative Disclosures, Lowest Current Credit Rating [Abstract]
Available-for-sale Securities, Portfolio Concentration US Govt or GSE Securities Not Rated, Amortized Cost	0	[3]				0	[3]
Available-for-sale Securities, Portfolio Concentration US Govt or GSE Securities Not Rated, Fair Value	0	[3]				0	[3]
Available-for-sale securities, Portfolio Concentration Rated AAA To AA, Amortized Cost	5,400,000					5,400,000
Available-for-sale Securities, Portfolio Concentration Rated AAA To AA, Fair Value	5,399,000					5,399,000
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Amortized Cost	30,280,000					30,280,000
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Fair Value	30,990,000					30,990,000
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value	0					0
Available-for-sale Securities, Portfolio Concentration Not Rated, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Not Rated, Fair Value	0					0
Residential Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	9,973,552,000		9,800,457,000			9,973,552,000
Available-for-sale Securities, Fair Value	10,214,984,000		10,007,343,000			10,214,984,000
Available-for-sale Securities, Gross Unrealized Gains	246,910,000	[1]	290,795,000	[1]		246,910,000	[1]
Available-for-sale Securities, Gross Unrealized Losses	1,295,000	[1]	11,103,000	[1]		1,295,000	[1]
Available-for-Sale Securities, Other Than Temporary Impairments	4,183,000	[2]	72,806,000	[2]		4,183,000	[2]
Available-for-sale Securities, Debt Maturities, Nominal Yield [Abstract]
Available-for-sale Securities, Debt Maturities, Nominal Yield	2.27%	[7]				2.27%	[7]
Available-for-sale Securities, Debt Maturities, Average Expected Life of Mortgage-backed Securities	2.5					2.5
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	35		70			35
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	161,828,000		78,871,000			161,828,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	131,159,000		411,023,000			131,159,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	292,987,000		489,894,000			292,987,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	1,161,000		849,000			1,161,000
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	4,317,000		83,060,000			4,317,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	5,478,000		83,909,000			5,478,000
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities, Portion Recognized In Earnings, Net Qualitative Disclosures, Lowest Current Credit Rating [Abstract]
Available-for-sale Securities, Portfolio Concentration US Govt or GSE Securities Not Rated, Amortized Cost	9,650,650,000	[3]				9,650,650,000	[3]
Available-for-sale Securities, Portfolio Concentration US Govt or GSE Securities Not Rated, Fair Value	9,889,821,000	[3]				9,889,821,000	[3]
Available-for-sale securities, Portfolio Concentration Rated AAA To AA, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Rated AAA To AA, Fair Value	0					0
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Fair Value	0					0
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Amortized Cost	322,902,000					322,902,000
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value	325,163,000					325,163,000
Available-for-sale Securities, Portfolio Concentration Not Rated, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Not Rated, Fair Value	0					0
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	9,650,650,000		9,297,389,000			9,650,650,000
Available-for-sale Securities, Fair Value	9,889,821,000		9,588,177,000			9,889,821,000
Available-for-sale Securities, Gross Unrealized Gains	240,332,000	[1]	290,795,000	[1]		240,332,000	[1]
Available-for-sale Securities, Gross Unrealized Losses	1,161,000	[1]	7,000	[1]		1,161,000	[1]
Available-for-Sale Securities, Other Than Temporary Impairments	0	[2]	0	[2]		0	[2]
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	12		3			12
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	161,828,000		70,729,000			161,828,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0		0			0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	161,828,000		70,729,000			161,828,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	1,161,000		7,000			1,161,000
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	0		0			0
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	1,161,000		7,000			1,161,000
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities, Portion Recognized In Earnings, Net Qualitative Disclosures, Lowest Current Credit Rating [Abstract]
Available-for-sale Securities, Portfolio Concentration US Govt or GSE Securities Not Rated, Amortized Cost	9,650,650,000	[3]				9,650,650,000	[3]
Available-for-sale Securities, Portfolio Concentration US Govt or GSE Securities Not Rated, Fair Value	9,889,821,000	[3]				9,889,821,000	[3]
Available-for-sale securities, Portfolio Concentration Rated AAA To AA, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Rated AAA To AA, Fair Value	0					0
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Fair Value	0					0
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value	0					0
Available-for-sale Securities, Portfolio Concentration Not Rated, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Not Rated, Fair Value	0					0
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | Federal National Mortgage Association Certificates and Obligations (FNMA) [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	5,308,463,000		5,823,972,000			5,308,463,000
Available-for-sale Securities, Fair Value	5,453,549,000		5,987,287,000			5,453,549,000
Available-for-sale Securities, Gross Unrealized Gains	146,247,000	[1]	163,319,000	[1]		146,247,000	[1]
Available-for-sale Securities, Gross Unrealized Losses	(1,161,000)	[1]	(4,000)	[1]		(1,161,000)	[1]
Available-for-Sale Securities, Other Than Temporary Impairments	0	[2]	0	[2]		0	[2]
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	12		2			12
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	161,828,000		68,657,000			161,828,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0		0			0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	161,828,000		68,657,000			161,828,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	1,161,000		4,000			1,161,000
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	0		0			0
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	1,161,000		4,000			1,161,000
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities, Portion Recognized In Earnings, Net Qualitative Disclosures, Lowest Current Credit Rating [Abstract]
Available-for-sale Securities, Portfolio Concentration US Govt or GSE Securities Not Rated, Amortized Cost	5,308,463,000	[3]				5,308,463,000	[3]
Available-for-sale Securities, Portfolio Concentration US Govt or GSE Securities Not Rated, Fair Value	5,453,549,000	[3]				5,453,549,000	[3]
Available-for-sale securities, Portfolio Concentration Rated AAA To AA, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Rated AAA To AA, Fair Value	0					0
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Fair Value	0					0
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value	0					0
Available-for-sale Securities, Portfolio Concentration Not Rated, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Not Rated, Fair Value	0					0
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | Federal Home Loan Mortgage Corporation Certificates and Obligations (FHLMC) [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	2,978,608,000		2,756,180,000			2,978,608,000
Available-for-sale Securities, Fair Value	3,045,564,000		2,846,215,000			3,045,564,000
Available-for-sale Securities, Gross Unrealized Gains	66,956,000	[1]	90,035,000	[1]		66,956,000	[1]
Available-for-sale Securities, Gross Unrealized Losses	0	[1]	0	[1]		0	[1]
Available-for-Sale Securities, Other Than Temporary Impairments	0	[2]	0	[2]		0	[2]
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	0		0			0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	0		0			0
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0		0			0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	0		0			0
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	0		0			0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	0		0			0
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	0		0			0
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities, Portion Recognized In Earnings, Net Qualitative Disclosures, Lowest Current Credit Rating [Abstract]
Available-for-sale Securities, Portfolio Concentration US Govt or GSE Securities Not Rated, Amortized Cost	2,978,608,000	[3]				2,978,608,000	[3]
Available-for-sale Securities, Portfolio Concentration US Govt or GSE Securities Not Rated, Fair Value	3,045,564,000	[3]				3,045,564,000	[3]
Available-for-sale securities, Portfolio Concentration Rated AAA To AA, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Rated AAA To AA, Fair Value	0					0
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Fair Value	0					0
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value	0					0
Available-for-sale Securities, Portfolio Concentration Not Rated, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Not Rated, Fair Value	0					0
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | Government National Mortgage Association Certificates and Obligations (GNMA) [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	1,215,554,000		647,569,000			1,215,554,000
Available-for-sale Securities, Fair Value	1,237,041,000		678,924,000			1,237,041,000
Available-for-sale Securities, Gross Unrealized Gains	21,487,000	[1]	31,358,000	[1]		21,487,000	[1]
Available-for-sale Securities, Gross Unrealized Losses	0	[1]	(3,000)	[1]		0	[1]
Available-for-Sale Securities, Other Than Temporary Impairments	0	[2]	0	[2]		0	[2]
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	0		1			0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	0		2,072,000			0
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0		0			0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	0		2,072,000			0
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	0		3,000			0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	0		0			0
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	0		3,000			0
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities, Portion Recognized In Earnings, Net Qualitative Disclosures, Lowest Current Credit Rating [Abstract]
Available-for-sale Securities, Portfolio Concentration US Govt or GSE Securities Not Rated, Amortized Cost	1,215,554,000	[3]				1,215,554,000	[3]
Available-for-sale Securities, Portfolio Concentration US Govt or GSE Securities Not Rated, Fair Value	1,237,041,000	[3]				1,237,041,000	[3]
Available-for-sale securities, Portfolio Concentration Rated AAA To AA, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Rated AAA To AA, Fair Value	0					0
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Fair Value	0					0
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value	0					0
Available-for-sale Securities, Portfolio Concentration Not Rated, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Not Rated, Fair Value	0					0
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | U.S. agency residental mortgage backed securities - Other [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	148,025,000		69,668,000			148,025,000
Available-for-sale Securities, Fair Value	153,667,000		75,751,000			153,667,000
Available-for-sale Securities, Gross Unrealized Gains	5,642,000	[1]	6,083,000	[1]		5,642,000	[1]
Available-for-sale Securities, Gross Unrealized Losses	0	[1]	0	[1]		0	[1]
Available-for-Sale Securities, Other Than Temporary Impairments	0	[2]	0	[2]		0	[2]
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities, Portion Recognized In Earnings, Net Qualitative Disclosures, Lowest Current Credit Rating [Abstract]
Available-for-sale Securities, Portfolio Concentration US Govt or GSE Securities Not Rated, Amortized Cost	148,025,000	[3]				148,025,000	[3]
Available-for-sale Securities, Portfolio Concentration US Govt or GSE Securities Not Rated, Fair Value	153,667,000	[3]				153,667,000	[3]
Available-for-sale securities, Portfolio Concentration Rated AAA To AA, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Rated AAA To AA, Fair Value	0					0
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Fair Value	0					0
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value	0					0
Available-for-sale Securities, Portfolio Concentration Not Rated, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Not Rated, Fair Value	0					0
Privately Issued Residential Mortgage-backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	322,902,000		503,068,000			322,902,000
Available-for-sale Securities, Fair Value	325,163,000		419,166,000			325,163,000
Available-for-sale Securities, Gross Unrealized Gains	6,578,000	[1]	0	[1]		6,578,000	[1]
Available-for-sale Securities, Gross Unrealized Losses	134,000	[1]	11,096,000	[1]		134,000	[1]
Available-for-Sale Securities, Other Than Temporary Impairments	4,183,000	[2]	72,806,000	[2]		4,183,000	[2]
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	23	[8]	67	[8]		23	[8]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	0	[8]	8,142,000	[8]		0	[8]
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	131,159,000	[8]	411,023,000	[8]		131,159,000	[8]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	131,159,000	[8]	419,165,000	[8]		131,159,000	[8]
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	0	[8]	842,000	[8]		0	[8]
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	4,317,000	[8]	83,060,000	[8]		4,317,000	[8]
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	4,317,000	[8]	83,902,000	[8]		4,317,000	[8]
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities, Portion Recognized In Earnings, Net Qualitative Disclosures, Lowest Current Credit Rating [Abstract]
Available-for-sale Securities, Portfolio Concentration US Govt or GSE Securities Not Rated, Amortized Cost	0	[3]				0	[3]
Available-for-sale Securities, Portfolio Concentration US Govt or GSE Securities Not Rated, Fair Value	0	[3]				0	[3]
Available-for-sale securities, Portfolio Concentration Rated AAA To AA, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Rated AAA To AA, Fair Value	0					0
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Fair Value	0					0
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Amortized Cost	322,902,000					322,902,000
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value	325,163,000					325,163,000
Available-for-sale Securities, Portfolio Concentration Not Rated, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Not Rated, Fair Value	0					0
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities, Portion Recognized in Earnings, Net Qualitative Disclosures, Privately Issued Mortgage-backed Securities [Abstract]
Available-for-sale Securities, Privately Issued Residential Mortgage-backed Securities, Number of Securities	49					49
Available-for-sale Securities, Privately Issued Residential Mortgage-backed Securities, Credit losses Recognized [Abstract]
Available-for-sale Securities, Privately Issued Residential Mortgage-backed Securities, Number of Securities with Credit Losses In Current Period	18					47
Amount of Credit Losses Recognized in Current Period	5,882,000		(21,900,000)		(26,500,000)	71,640,000
Other Than Temporary Impairment Losses, Investments, Available-for-sale Securities, Portion Recognized in Earnings, Net, Qualitative Disclosures, Assumptions Used to Develop Projected Cash Flows [Abstract]
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities, Qualitative Disclosures, Projected Unemployment Rate, Next 12 Months	8.50%		9.50%			8.50%
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities, Qualitative Disclosures, Projected Unemployment Rate, Months 13-21	8.00%		8.00%			8.00%
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities, Qualitative Disclosures, Projected Unemployment Rate, Months 22 and Thereafter	8.00%		8.00%			8.00%
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities, Qualitative Disclosures, Projected Housing Price Depreciation, Next Twelve Months	2.00%		8.00%			2.00%
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities, Qualitative Disclosures, Projected Housing Price Depreciation, Thereafter	2.00%		2.00%			2.00%
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities, Qualitative Disclosures, Discount Rate, Minimum	2.00%		2.00%			2.00%
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities, Qualitative Disclosures, Discount Rate, Minimum	6.25%		6.25%			6.25%
Privately Issued Residential Mortgage-backed Securities [Member] | Alt A [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	124,314,000		168,461,000			124,314,000
Available-for-sale Securities, Fair Value	123,174,000		132,242,000			123,174,000
Available-for-sale Securities, Gross Unrealized Gains	1,440,000	[1]	0	[1]		1,440,000	[1]
Available-for-sale Securities, Gross Unrealized Losses	0	[1]	0	[1]		0	[1]
Available-for-Sale Securities, Other Than Temporary Impairments	(2,580,000)	[2]	(36,219,000)	[2]		(2,580,000)	[2]
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	12	[8]	19	[8]		12	[8]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, OTTI Portion, Number of Positions	12		19			12
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	0	[8]	0	[8]		0	[8]
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	87,907,000	[8]	132,242,000	[8]		87,907,000	[8]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	87,907,000	[8]	132,242,000	[8]		87,907,000	[8]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less Than Twelve Months, OTTI Portion, Fair Value	0		0			0
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, OTTI Portion, Fair Value	87,907,000		132,242,000			87,907,000
Available-for-sale Securities, Continuous Unrealized Loss Position, OTTI Portion, Fair Value	87,907,000		132,242,000			87,907,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	0	[8]	0	[8]		0	[8]
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	2,580,000	[8]	36,219,000	[8]		2,580,000	[8]
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	2,580,000	[8]	36,219,000	[8]		2,580,000	[8]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	0		0			0
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, OTTI Portion, Aggregate Losses	2,580,000		36,219,000			2,580,000
Available-for-sale Securities, Continuous Unrealized Loss Position, OTTI Portion, Aggregate Losses	2,580,000		36,219,000			2,580,000
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities, Portion Recognized In Earnings, Net Qualitative Disclosures, Lowest Current Credit Rating [Abstract]
Available-for-sale Securities, Portfolio Concentration US Govt or GSE Securities Not Rated, Amortized Cost	0	[3]				0	[3]
Available-for-sale Securities, Portfolio Concentration US Govt or GSE Securities Not Rated, Fair Value	0	[3]				0	[3]
Available-for-sale securities, Portfolio Concentration Rated AAA To AA, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Rated AAA To AA, Fair Value	0					0
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Fair Value	0					0
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Amortized Cost	124,314,000					124,314,000
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value	123,174,000					123,174,000
Available-for-sale Securities, Portfolio Concentration Not Rated, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Not Rated, Fair Value	0					0
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities, Portion Recognized in Earnings, Net Qualitative Disclosures, Privately Issued Mortgage-backed Securities [Abstract]
Available-for-sale Securities, Privately Issued Residential Mortgage-backed Securities, Number of Securities	16					16
Available-for-sale Securities, Privately Issued Residential Mortgage-backed Securities, Credit losses Recognized [Abstract]
Available-for-sale Securities, Privately Issued Residential Mortgage-backed Securities, Number of Securities with Credit Losses In Current Period	11					16
Amount of Credit Losses Recognized in Current Period	4,469,000					48,188,000
Privately Issued Residential Mortgage-backed Securities [Member] | Jumbo A Loans [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	198,588,000		334,607,000			198,588,000
Available-for-sale Securities, Fair Value	201,989,000		286,924,000			201,989,000
Available-for-sale Securities, Gross Unrealized Gains	5,138,000	[1]	0	[1]		5,138,000	[1]
Available-for-sale Securities, Gross Unrealized Losses	(134,000)	[1]	(11,096,000)	[1]		(134,000)	[1]
Available-for-Sale Securities, Other Than Temporary Impairments	(1,603,000)	[2]	(36,587,000)	[2]		(1,603,000)	[2]
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	11	[8]	48	[8]		11	[8]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, OTTI Portion, Number of Positions	10		36			10
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	0	[8]	8,142,000	[8]		0	[8]
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	43,252,000	[8]	278,781,000	[8]		43,252,000	[8]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	43,252,000	[8]	286,923,000	[8]		43,252,000	[8]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less Than Twelve Months, OTTI Portion, Fair Value	0		3,809,000			0
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, OTTI Portion, Fair Value	29,128,000		202,874,000			29,128,000
Available-for-sale Securities, Continuous Unrealized Loss Position, OTTI Portion, Fair Value	29,128,000		206,683,000			29,128,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	0	[8]	842,000	[8]		0	[8]
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	1,737,000	[8]	46,841,000	[8]		1,737,000	[8]
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	1,737,000	[8]	47,683,000	[8]		1,737,000	[8]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	0		256,000			0
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, OTTI Portion, Aggregate Losses	1,602,000		36,331,000			1,602,000
Available-for-sale Securities, Continuous Unrealized Loss Position, OTTI Portion, Aggregate Losses	1,602,000		36,587,000			1,602,000
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities, Portion Recognized In Earnings, Net Qualitative Disclosures, Lowest Current Credit Rating [Abstract]
Available-for-sale Securities, Portfolio Concentration US Govt or GSE Securities Not Rated, Amortized Cost	0	[3]				0	[3]
Available-for-sale Securities, Portfolio Concentration US Govt or GSE Securities Not Rated, Fair Value	0	[3]				0	[3]
Available-for-sale securities, Portfolio Concentration Rated AAA To AA, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Rated AAA To AA, Fair Value	0					0
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Fair Value	0					0
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Amortized Cost	198,588,000					198,588,000
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value	201,989,000					201,989,000
Available-for-sale Securities, Portfolio Concentration Not Rated, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Not Rated, Fair Value	0					0
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities, Portion Recognized in Earnings, Net Qualitative Disclosures, Privately Issued Mortgage-backed Securities [Abstract]
Available-for-sale Securities, Privately Issued Residential Mortgage-backed Securities, Number of Securities	33					33
Available-for-sale Securities, Privately Issued Residential Mortgage-backed Securities, Credit losses Recognized [Abstract]
Available-for-sale Securities, Privately Issued Residential Mortgage-backed Securities, Number of Securities with Credit Losses In Current Period	7					31
Amount of Credit Losses Recognized in Current Period	1,413,000					23,452,000
Commercial Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	890,746,000					890,746,000
Available-for-sale Securities, Fair Value	895,075,000					895,075,000
Available-for-sale Securities, Gross Unrealized Gains	5,006,000	[1]				5,006,000	[1]
Available-for-sale Securities, Gross Unrealized Losses	(677,000)	[1]				(677,000)	[1]
Available-for-Sale Securities, Other Than Temporary Impairments	0	[2]				0	[2]
Available-for-sale Securities, Debt Maturities, Nominal Yield [Abstract]
Available-for-sale Securities, Debt Maturities, Nominal Yield	1.35%					1.35%
Available-for-sale Securities, Debt Maturities, Weighted Average Maturity	7.09	[5]				7.09	[5]
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	8					8
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	275,065,000					275,065,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0					0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	275,065,000					275,065,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	677,000					677,000
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	0					0
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	677,000					677,000
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities, Portion Recognized In Earnings, Net Qualitative Disclosures, Lowest Current Credit Rating [Abstract]
Available-for-sale Securities, Portfolio Concentration US Govt or GSE Securities Not Rated, Amortized Cost	890,746,000	[3]				890,746,000	[3]
Available-for-sale Securities, Portfolio Concentration US Govt or GSE Securities Not Rated, Fair Value	895,075,000	[3]				895,075,000	[3]
Available-for-sale securities, Portfolio Concentration Rated AAA To AA, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Rated AAA To AA, Fair Value	0					0
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Fair Value	0					0
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value	0					0
Available-for-sale Securities, Portfolio Concentration Not Rated, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Not Rated, Fair Value	0					0
Perpetual Preferred, Equity Securities and Mutual Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	46,764,000					46,764,000
Available-for-sale Securities, Fair Value	52,629,000					52,629,000
Available-for-sale Securities, Debt Maturities, Nominal Yield [Abstract]
Available-for-sale Securities, Debt Maturities, Nominal Yield	1.12%					1.12%
Preferred Stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	22,171,000		19,171,000			22,171,000
Available-for-sale Securities, Fair Value	25,072,000		18,446,000			25,072,000
Available-for-sale Securities, Gross Unrealized Gains	2,901,000	[1]	1,030,000	[1]		2,901,000	[1]
Available-for-sale Securities, Gross Unrealized Losses	0	[1]	(1,755,000)	[1]		0	[1]
Available-for-Sale Securities, Other Than Temporary Impairments	0	[2]	0	[2]		0	[2]
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	0		6			0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	0		11,147,000			0
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	0		0			0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	0		11,147,000			0
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	0		1,755,000			0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	0		0			0
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	0		1,755,000			0
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities, Portion Recognized In Earnings, Net Qualitative Disclosures, Lowest Current Credit Rating [Abstract]
Available-for-sale Securities, Portfolio Concentration US Govt or GSE Securities Not Rated, Amortized Cost	0	[3]				0	[3]
Available-for-sale Securities, Portfolio Concentration US Govt or GSE Securities Not Rated, Fair Value	0	[3]				0	[3]
Available-for-sale securities, Portfolio Concentration Rated AAA To AA, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Rated AAA To AA, Fair Value	0					0
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Amortized Cost	22,171,000					22,171,000
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Fair Value	25,072,000					25,072,000
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value	0					0
Available-for-sale Securities, Portfolio Concentration Not Rated, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Not Rated, Fair Value	0					0
Equity Securities And Mutual Funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost Basis	24,593,000		33,843,000			24,593,000
Available-for-sale Securities, Fair Value	27,557,000		47,238,000			27,557,000
Available-for-sale Securities, Gross Unrealized Gains	3,242,000	[1]	13,727,000	[1]		3,242,000	[1]
Available-for-sale Securities, Gross Unrealized Losses	(278,000)	[1]	(332,000)	[1]		(278,000)	[1]
Available-for-Sale Securities, Other Than Temporary Impairments	0	[2]	0	[2]		0	[2]
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	22		7			22
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value	202,000		221,000			202,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value	2,161,000		2,551,000			2,161,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value	2,363,000		2,772,000			2,363,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Aggregate Losses	1,000		5,000			1,000
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Losses	277,000		327,000			277,000
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses	278,000		332,000			278,000
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities, Portion Recognized In Earnings, Net Qualitative Disclosures, Lowest Current Credit Rating [Abstract]
Available-for-sale Securities, Portfolio Concentration US Govt or GSE Securities Not Rated, Amortized Cost	0	[3]				0	[3]
Available-for-sale Securities, Portfolio Concentration US Govt or GSE Securities Not Rated, Fair Value	0	[3]				0	[3]
Available-for-sale securities, Portfolio Concentration Rated AAA To AA, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Rated AAA To AA, Fair Value	0					0
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Fair Value	0					0
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Amortized Cost	0					0
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value	0					0
Available-for-sale Securities, Portfolio Concentration Not Rated, Amortized Cost	24,593,000					24,593,000
Available-for-sale Securities, Portfolio Concentration Not Rated, Fair Value	27,557,000					27,557,000
Available-for-sale Securities, Privately Issued Residential Mortgage-backed Securities, Credit losses Recognized [Abstract]
Amount of Credit Losses Recognized in Current Period	$ (457,000)		$ 0		$ (327,000)

[1] Gross unrealized gain/ loss recognized in AOCI in the consolidated balance sheet.

[2] Amounts represent unrealized loss that remains in AOCI after an other-than-temporary credit loss has been recognized in income.

[3] U.S. government and government sponsored enterprises are not rated by the nationally-recognized rating agencies as these securities are guaranteed by agencies of the U.S. government or government-sponsored enterprises.

[4] Nominal yield on municipal and other tax-exempt securities and other debt securities with contractual maturity dates over ten years are based on variable rates which generally are reset within 35 days.

[5] Expected maturities may differ from contractual maturities, because borrowers may have the right to call or prepay obligations with or without penalty.

[6] Calculated on a taxable equivalent basis using a 39% effective tax rate.

[7] The nominal yield on mortgage-backed securities is based upon prepayment assumptions at the purchase date. Actual yields earned may differ significantly based upon actual prepayments.

[8] Includes the following securities for which an unrealized loss remains in AOCI after an other-than-temporary credit loss has been recognized in income: