Available for Sale Securities (Details) $ in Thousands		3 Months Ended						6 Months Ended				90 Months Ended
		Jun. 30, 2016 USD ($)		Dec. 31, 2015 USD ($)		Jun. 30, 2015 USD ($)		Jun. 30, 2016 USD ($)		Jun. 30, 2015 USD ($)		Jun. 30, 2016 USD ($)
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost		$ 8,635,304		$ 9,004,624		$ 8,910,959		$ 8,635,304		$ 8,910,959		$ 8,635,304
Available-for-sale Securities, Fair Value		8,830,689		9,042,733		9,000,117		8,830,689		9,000,117		8,830,689
Available-for-sale Securities, Gross Unrealized Gain		198,378	[1]	79,970	[2]	114,955	[3]	198,378	[1]	114,955	[3]	198,378	[1]
Available-for-sale Securities, Gross Unrealized Loss		(2,217)	[1]	(41,034)	[2]	(24,958)	[3]	(2,217)	[1]	(24,958)	[3]	(2,217)	[1]
Available-for-Sale Securities, Other Than Temporary Impairments		(776)	[4]	(827)	[5]	(839)	[6]	(776)	[4]	(839)	[6]	(776)	[4]
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Amortized Cost		8,635,304		9,004,624		8,910,959		8,635,304		8,910,959		8,635,304
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Fair Value		$ 8,830,689		9,042,733		9,000,117		$ 8,830,689		9,000,117		$ 8,830,689
Available-for-sale Securities, Debt Maturities, Nominal Yield [Abstract]
Available-for-sale Securities, Debt Maturities, Nominal Yield		1.86%						1.86%				1.86%
Available-for-sale Securities, Gross Realized Gain (Loss), Disclosures [Abstract]
Available-for-sale Securities, Proceeds		$ 325,758				378,835		$ 795,140		713,660
Available-for-sale Securities, Gross realized gains		5,326				4,840		9,290		9,740
Available-for-sale Securities, Gross realized losses		0				(1,407)		0		(1,980)
Available-for-sale Securities, Related federal and state income tax expense		2,072				1,335		3,614		3,018
Available-for-sale Securities, Pledged as Collateral [Abstract]
Available-for-sale Securities, Pledged As Collateral, Amortized cost		7,502,361		6,831,743		6,035,423		7,502,361		6,035,423		$ 7,502,361
Available-for-sale Securities, Pledged As Collateral, Fair value		$ 7,657,916		$ 6,849,524		$ 6,089,438		$ 7,657,916		$ 6,089,438		$ 7,657,916
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions		90		419		264		90		264		90
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		$ 567,460		$ 3,873,809		$ 1,534,531		$ 567,460		$ 1,534,531		$ 567,460
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		135,093		716,700		1,168,029		135,093		1,168,029		135,093
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		702,553		4,590,509		2,702,560		702,553		2,702,560		702,553
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		1,193		28,496		10,260		1,193		10,260		1,193
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		1,800		13,365		15,537		1,800		15,537		1,800
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		2,993		41,861		25,797		2,993		25,797		2,993
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 Rated AAA To AA, Amortized Cost		32,245						32,245				32,245
Available-for-sale Securities, Portfolio Concentration Rated AAA To AA, Fair Value		33,047						33,047				33,047
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Amortized Cost		14,417						14,417				14,417
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Fair Value		14,568						14,568				14,568
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Amortized Cost		126,075						126,075				126,075
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value		138,701						138,701				138,701
Available-for-sale Securities, Portfolio Concentration Not Rated, Amortized Cost		8,462,567						8,462,567				8,462,567
Available-for-sale Securities, Portfolio Concentration Not Rated, Fair Value		8,644,373						8,644,373				8,644,373
Fixed Maturity Securities [Member]
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Less than One Year, Amortized Cost Basis		9,693						9,693				9,693
Available-for-sale Securities, Debt Maturities, One to Five Years, Amortized Cost Basis		922,252						922,252				922,252
Available-for-sale Securities, Debt Maturities, Six To Ten Years, Amortized Cost Basis		1,763,688						1,763,688				1,763,688
Available-for-sale Securities, Debt Maturities, Over Ten Years, Amortized Cost Basis		214,243						214,243				214,243
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis		2,909,876						2,909,876				2,909,876
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Less than One Year, Fair Value		9,781						9,781				9,781
Available-for-sale Securities, Debt Maturities, One to Five Years, Fair Value		936,793						936,793				936,793
Available-for-sale Securities, Debt Maturities, Six to Ten Years, Fair Value		1,805,364						1,805,364				1,805,364
Available-for-sale Securities, Debt Maturities, Over Ten Years, Fair Value		215,425						215,425				215,425
Available-for-sale Securities, Debt Maturities, Single Maturity Date		$ 2,967,363						$ 2,967,363				$ 2,967,363
Available-for-sale Securities, Debt Maturities, Nominal Yield [Abstract]
Available-for-sale Securities, Debt Maturities, Less than One Year, Nominal Yield		4.51%						4.51%				4.51%
Available-for-sale Securities, Debt Maturities, One to Five Years, Nominal Yield		1.71%						1.71%				1.71%
Available-for-sale Securities, Debt Maturities, Six To Ten Years, Nominal Yield		1.87%						1.87%				1.87%
Available-for-sale Securities, Debt Maturities, Over Ten Years, Nominal Yield		1.55%						1.55%				1.55%
Available-for-sale Securities, Debt Maturities, Nominal Yield		1.80%						1.80%				1.80%
Available-for-sale Securities, Debt Maturities, Weighted Average Maturity	[7]	6.97						6.97				6.97
U.S. Treasury [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost		$ 1,000		1,000		1,000		$ 1,000		1,000		$ 1,000
Available-for-sale Securities, Fair Value		1,004		995		1,000		1,004		1,000		1,004
Available-for-sale Securities, Gross Unrealized Gain		4	[1]	0	[2]	0	[3]	4	[1]	0	[3]	4	[1]
Available-for-sale Securities, Gross Unrealized Loss		0	[1]	(5)	[2]	0	[3]	0	[1]	0	[3]	0	[1]
Available-for-Sale Securities, Other Than Temporary Impairments		0	[4]	0	[5]	0	[6]	0	[4]	0	[6]	0	[4]
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Less than One Year, Amortized Cost Basis		0						0				0
Available-for-sale Securities, Debt Maturities, One to Five Years, Amortized Cost Basis		1,000						1,000				1,000
Available-for-sale Securities, Debt Maturities, Six To Ten Years, Amortized Cost Basis		0						0				0
Available-for-sale Securities, Debt Maturities, Over Ten Years, Amortized Cost Basis		0						0				0
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis		1,000						1,000				1,000
Available-for-sale Securities, Debt Maturities, Amortized Cost		1,000		1,000		1,000		1,000		1,000		1,000
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Less than One Year, Fair Value		0						0				0
Available-for-sale Securities, Debt Maturities, One to Five Years, Fair Value		1,004						1,004				1,004
Available-for-sale Securities, Debt Maturities, Six to Ten Years, Fair Value		0						0				0
Available-for-sale Securities, Debt Maturities, Over Ten Years, Fair Value		0						0				0
Available-for-sale Securities, Debt Maturities, Single Maturity Date		1,004						1,004				1,004
Available-for-sale Securities, Debt Maturities, Fair Value		$ 1,004		$ 995		1,000		$ 1,004		1,000		$ 1,004
Available-for-sale Securities, Debt Maturities, Nominal Yield [Abstract]
Available-for-sale Securities, Debt Maturities, Less than One Year, Nominal Yield		0.00%						0.00%				0.00%
Available-for-sale Securities, Debt Maturities, One to Five Years, Nominal Yield		0.87%						0.87%				0.87%
Available-for-sale Securities, Debt Maturities, Six To Ten Years, Nominal Yield		0.00%						0.00%				0.00%
Available-for-sale Securities, Debt Maturities, Over Ten Years, Nominal Yield		0.00%						0.00%				0.00%
Available-for-sale Securities, Debt Maturities, Nominal Yield		0.87%						0.87%				0.87%
Available-for-sale Securities, Debt Maturities, Weighted Average Maturity	[7]	1.55						1.55				1.55
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions				1
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				$ 995
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value				0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value				995
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss				5
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss				0
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss				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 Rated AAA To AA, Amortized Cost		$ 0						$ 0				$ 0
Available-for-sale Securities, Portfolio Concentration Rated AAA To AA, Fair Value		0						0				0
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Amortized Cost		0						0				0
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Fair Value		0						0				0
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Amortized Cost		0						0				0
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value		0						0				0
Available-for-sale Securities, Portfolio Concentration Not Rated, Amortized Cost		1,000						1,000				1,000
Available-for-sale Securities, Portfolio Concentration Not Rated, Fair Value		1,004						1,004				1,004
Municipal and other tax-exempt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost		50,170		56,681		61,341		50,170		61,341		50,170
Available-for-sale Securities, Fair Value		50,262		56,817		61,624		50,262		61,624		50,262
Available-for-sale Securities, Gross Unrealized Gain		805	[1]	873	[2]	1,028	[3]	805	[1]	1,028	[3]	805	[1]
Available-for-sale Securities, Gross Unrealized Loss		(713)	[1]	(737)	[2]	(745)	[3]	(713)	[1]	(745)	[3]	(713)	[1]
Available-for-Sale Securities, Other Than Temporary Impairments		0	[4]	0	[5]	0	[6]	0	[4]	0	[6]	0	[4]
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Less than One Year, Amortized Cost Basis		9,693						9,693				9,693
Available-for-sale Securities, Debt Maturities, One to Five Years, Amortized Cost Basis		16,270						16,270				16,270
Available-for-sale Securities, Debt Maturities, Six To Ten Years, Amortized Cost Basis		2,806						2,806				2,806
Available-for-sale Securities, Debt Maturities, Over Ten Years, Amortized Cost Basis		21,401						21,401				21,401
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis		50,170						50,170				50,170
Available-for-sale Securities, Debt Maturities, Amortized Cost		50,170		56,681		61,341		50,170		61,341		50,170
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Less than One Year, Fair Value		9,781						9,781				9,781
Available-for-sale Securities, Debt Maturities, One to Five Years, Fair Value		16,636						16,636				16,636
Available-for-sale Securities, Debt Maturities, Six to Ten Years, Fair Value		2,867						2,867				2,867
Available-for-sale Securities, Debt Maturities, Over Ten Years, Fair Value		20,978						20,978				20,978
Available-for-sale Securities, Debt Maturities, Single Maturity Date		50,262						50,262				50,262
Available-for-sale Securities, Debt Maturities, Fair Value		$ 50,262		$ 56,817		$ 61,624		$ 50,262		$ 61,624		$ 50,262
Available-for-sale Securities, Debt Maturities, Nominal Yield [Abstract]
Available-for-sale Securities, Debt Maturities, Less than One Year, Nominal Yield	[8]	4.51%						4.51%				4.51%
Available-for-sale Securities, Debt Maturities, One to Five Years, Nominal Yield	[8]	4.11%						4.11%				4.11%
Available-for-sale Securities, Debt Maturities, Six To Ten Years, Nominal Yield	[8]	3.70%						3.70%				3.70%
Available-for-sale Securities, Debt Maturities, Over Ten Years, Nominal Yield	[8],[9]	2.01%						2.01%				2.01%
Available-for-sale Securities, Debt Maturities, Nominal Yield	[8]	3.27%						3.27%				3.27%
Available-for-sale Securities, Debt Maturities, Weighted Average Maturity	[7]	8.43						8.43				8.43
Available-for-sale Securities, Debt Maturities, Effective tax rate for nominal yield calculation		39.00%						39.00%				39.00%
Available-for-sale Securities, Debt Maturities, Number of days for interest rates to reset		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		17		20		20		17		20		17
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		$ 375		$ 9,909		$ 9,855		$ 375		$ 9,855		$ 375
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		10,289		11,664		11,688		10,289		11,688		10,289
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		10,664		21,573		21,543		10,664		21,543		10,664
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		0		27		41		0		41		0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		713		710		704		713		704		713
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		713		737		745		713		745		713
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 Rated AAA To AA, Amortized Cost		27,841						27,841				27,841
Available-for-sale Securities, Portfolio Concentration Rated AAA To AA, Fair Value		28,404						28,404				28,404
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Amortized Cost		9,621						9,621				9,621
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Fair Value		9,025						9,025				9,025
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Amortized Cost		0						0				0
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value		0						0				0
Available-for-sale Securities, Portfolio Concentration Not Rated, Amortized Cost		12,708						12,708				12,708
Available-for-sale Securities, Portfolio Concentration Not Rated, Fair Value		12,833						12,833				12,833
Commercial mortgage-backed securities guaranteed by U.S. government agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost		2,854,306		2,919,044		2,405,480		2,854,306		2,405,480		2,854,306
Available-for-sale Securities, Fair Value		2,911,946		2,905,796		2,401,364		2,911,946		2,401,364		2,911,946
Available-for-sale Securities, Gross Unrealized Gain		57,762	[1]	5,396	[2]	7,988	[3]	57,762	[1]	7,988	[3]	57,762	[1]
Available-for-sale Securities, Gross Unrealized Loss		(122)	[1]	(18,644)	[2]	(12,104)	[3]	(122)	[1]	(12,104)	[3]	(122)	[1]
Available-for-Sale Securities, Other Than Temporary Impairments		0	[4]	0	[5]	0	[6]	0	[4]	0	[6]	0	[4]
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Less than One Year, Amortized Cost Basis		0						0				0
Available-for-sale Securities, Debt Maturities, One to Five Years, Amortized Cost Basis		904,982						904,982				904,982
Available-for-sale Securities, Debt Maturities, Six To Ten Years, Amortized Cost Basis		1,760,882						1,760,882				1,760,882
Available-for-sale Securities, Debt Maturities, Over Ten Years, Amortized Cost Basis		188,442						188,442				188,442
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis		2,854,306						2,854,306				2,854,306
Available-for-sale Securities, Debt Maturities, Amortized Cost		2,854,306		2,919,044		2,405,480		2,854,306		2,405,480		2,854,306
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Less than One Year, Fair Value		0						0				0
Available-for-sale Securities, Debt Maturities, One to Five Years, Fair Value		919,153						919,153				919,153
Available-for-sale Securities, Debt Maturities, Six to Ten Years, Fair Value		1,802,497						1,802,497				1,802,497
Available-for-sale Securities, Debt Maturities, Over Ten Years, Fair Value		190,296						190,296				190,296
Available-for-sale Securities, Debt Maturities, Single Maturity Date		2,911,946						2,911,946				2,911,946
Available-for-sale Securities, Debt Maturities, Fair Value		$ 2,911,946		$ 2,905,796		$ 2,401,364		$ 2,911,946		$ 2,401,364		$ 2,911,946
Available-for-sale Securities, Debt Maturities, Nominal Yield [Abstract]
Available-for-sale Securities, Debt Maturities, Less than One Year, Nominal Yield		0.00%						0.00%				0.00%
Available-for-sale Securities, Debt Maturities, One to Five Years, Nominal Yield		1.66%						1.66%				1.66%
Available-for-sale Securities, Debt Maturities, Six To Ten Years, Nominal Yield		1.87%						1.87%				1.87%
Available-for-sale Securities, Debt Maturities, Over Ten Years, Nominal Yield		1.50%						1.50%				1.50%
Available-for-sale Securities, Debt Maturities, Nominal Yield		1.78%						1.78%				1.78%
Available-for-sale Securities, Debt Maturities, Weighted Average Maturity	[7]	6.91						6.91				6.91
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		213		128		11		128		11
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		$ 103,955		$ 1,582,469		$ 712,973		$ 103,955		$ 712,973		$ 103,955
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		65,857		484,258		791,108		65,857		791,108		65,857
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		169,812		2,066,727		1,504,081		169,812		1,504,081		169,812
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		37		11,419		3,848		37		3,848		37
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		85		7,225		8,256		85		8,256		85
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		122		18,644		12,104		122		12,104		122
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 Rated AAA To AA, Amortized Cost		0						0				0
Available-for-sale Securities, Portfolio Concentration Rated AAA To AA, Fair Value		0						0				0
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Amortized Cost		0						0				0
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Fair Value		0						0				0
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Amortized Cost		0						0				0
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value		0						0				0
Available-for-sale Securities, Portfolio Concentration Not Rated, Amortized Cost		2,854,306						2,854,306				2,854,306
Available-for-sale Securities, Portfolio Concentration Not Rated, Fair Value		2,911,946						2,911,946				2,911,946
Other debt securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost		4,400		4,400		4,400		4,400		4,400		4,400
Available-for-sale Securities, Fair Value		4,151		4,151		4,150		4,151		4,150		4,151
Available-for-sale Securities, Gross Unrealized Gain		0	[1]	0	[2]	0	[3]	0	[1]	0	[3]	0	[1]
Available-for-sale Securities, Gross Unrealized Loss		(249)	[1]	(249)	[2]	(250)	[3]	(249)	[1]	(250)	[3]	(249)	[1]
Available-for-Sale Securities, Other Than Temporary Impairments		0	[4]	0	[5]	0	[6]	0	[4]	0	[6]	0	[4]
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Less than One Year, Amortized Cost Basis		0						0				0
Available-for-sale Securities, Debt Maturities, One to Five Years, Amortized Cost Basis		0						0				0
Available-for-sale Securities, Debt Maturities, Six To Ten Years, Amortized Cost Basis		0						0				0
Available-for-sale Securities, Debt Maturities, Over Ten Years, Amortized Cost Basis		4,400						4,400				4,400
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis		4,400						4,400				4,400
Available-for-sale Securities, Debt Maturities, Amortized Cost		4,400		4,400		4,400		4,400		4,400		4,400
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Less than One Year, Fair Value		0						0				0
Available-for-sale Securities, Debt Maturities, One to Five Years, Fair Value		0						0				0
Available-for-sale Securities, Debt Maturities, Six to Ten Years, Fair Value		0						0				0
Available-for-sale Securities, Debt Maturities, Over Ten Years, Fair Value		4,151						4,151				4,151
Available-for-sale Securities, Debt Maturities, Single Maturity Date		4,151						4,151				4,151
Available-for-sale Securities, Debt Maturities, Fair Value		$ 4,151		$ 4,151		$ 4,150		$ 4,151		$ 4,150		$ 4,151
Available-for-sale Securities, Debt Maturities, Nominal Yield [Abstract]
Available-for-sale Securities, Debt Maturities, Less than One Year, Nominal Yield		0.00%						0.00%				0.00%
Available-for-sale Securities, Debt Maturities, One to Five Years, Nominal Yield		0.00%						0.00%				0.00%
Available-for-sale Securities, Debt Maturities, Six To Ten Years, Nominal Yield		0.00%						0.00%				0.00%
Available-for-sale Securities, Debt Maturities, Over Ten Years, Nominal Yield	[9]	1.71%						1.71%				1.71%
Available-for-sale Securities, Debt Maturities, Nominal Yield		0.00%						0.00%				0.00%
Available-for-sale Securities, Debt Maturities, Weighted Average Maturity	[7]	31.16						31.16				31.16
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions		2		2		2		2		2		2
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		$ 0		$ 0		$ 0
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		4,151		4,151		4,149		4,151		4,149		4,151
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		4,151		4,151		4,149		4,151		4,149		4,151
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		0		0		0		0		0		0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		249		249		250		249		250		249
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		249		249		250		249		250		249
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 Rated AAA To AA, Amortized Cost		4,400						4,400				4,400
Available-for-sale Securities, Portfolio Concentration Rated AAA To AA, Fair Value		4,151						4,151				4,151
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Amortized Cost		0						0				0
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Fair Value		0						0				0
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Amortized Cost		0						0				0
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value		0						0				0
Available-for-sale Securities, Portfolio Concentration Not Rated, Amortized Cost		0						0				0
Available-for-sale Securities, Portfolio Concentration Not Rated, Fair Value		0						0				0
Residential Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost		5,692,596		5,989,207		6,402,929		5,692,596		6,402,929		5,692,596
Available-for-sale Securities, Fair Value		5,826,581		6,037,469		6,493,599		5,826,581		6,493,599		5,826,581
Available-for-sale Securities, Gross Unrealized Gain		135,880	[1]	70,448	[2]	102,622	[3]	135,880	[1]	102,622	[3]	135,880	[1]
Available-for-sale Securities, Gross Unrealized Loss		(1,119)	[1]	(21,359)	[2]	(11,113)	[3]	(1,119)	[1]	(11,113)	[3]	(1,119)	[1]
Available-for-Sale Securities, Other Than Temporary Impairments		(776)	[4]	(827)	[5]	(839)	[6]	(776)	[4]	(839)	[6]	(776)	[4]
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Amortized Cost Basis		5,692,596						5,692,596				5,692,596
Available-for-sale Securities, Debt Maturities, Amortized Cost		5,692,596		5,989,207		6,402,929		5,692,596		6,402,929		5,692,596
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Fair Value		5,826,581						5,826,581				5,826,581
Available-for-sale Securities, Debt Maturities, Fair Value		$ 5,826,581		$ 6,037,469		$ 6,493,599		$ 5,826,581		$ 6,493,599		$ 5,826,581
Available-for-sale Securities, Debt Maturities, Nominal Yield [Abstract]
Available-for-sale Securities, Debt Maturities, Nominal Yield	[10]	1.90%						1.90%				1.90%
Available-for-sale Securities, Debt Maturities, Average Expected Life of Mortgage-backed Securities								3 years 120 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		30		122		63		30		63		30
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		$ 463,130		$ 2,279,654		$ 806,997		$ 463,130		$ 806,997		$ 463,130
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		53,907		215,636		360,090		53,907		360,090		53,907
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		517,037		2,495,290		1,167,087		517,037		1,167,087		517,037
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		1,156		17,040		5,657		1,156		5,657		1,156
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		739		5,146		6,295		739		6,295		739
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		1,895		22,186		11,952		1,895		11,952		1,895
U.S. government agency residential mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost		5,577,287	[11]	5,861,096		6,260,475		5,577,287	[11]	6,260,475		5,577,287	[11]
Available-for-sale Securities, Fair Value		5,700,268	[11]	5,898,351		6,339,449		5,700,268	[11]	6,339,449		5,700,268	[11]
Available-for-sale Securities, Gross Unrealized Gain		124,064	[1]	58,614	[2]	90,087	[3]	124,064	[1]	90,087	[3]	124,064	[1]
Available-for-sale Securities, Gross Unrealized Loss		(1,083)	[1]	(21,359)	[2]	(11,113)	[3]	(1,083)	[1]	(11,113)	[3]	(1,083)	[1]
Available-for-Sale Securities, Other Than Temporary Impairments		0	[4]	0	[5]	0	[6]	0	[4]	0	[6]	0	[4]
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Amortized Cost		5,577,287	[11]	5,861,096		6,260,475		5,577,287	[11]	6,260,475		5,577,287	[11]
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Fair Value		$ 5,700,268	[11]	$ 5,898,351		$ 6,339,449		$ 5,700,268	[11]	$ 6,339,449		$ 5,700,268	[11]
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions		16		110		48		16		48		16
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		$ 447,541		$ 2,279,654		$ 789,211		$ 447,541		$ 789,211		$ 447,541
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		37,739		197,890		350,780		37,739		350,780		37,739
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		485,280		2,477,544		1,139,991		485,280		1,139,991		485,280
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		879		17,040		5,172		879		5,172		879
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		204		4,319		5,941		204		5,941		204
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		1,083		21,359		11,113		1,083		11,113		1,083
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 Rated AAA To AA, Amortized Cost	[11]	0						0				0
Available-for-sale Securities, Portfolio Concentration Rated AAA To AA, Fair Value	[11]	0						0				0
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Amortized Cost	[11]	0						0				0
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Fair Value	[11]	0						0				0
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Amortized Cost	[11]	0						0				0
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value	[11]	0						0				0
Available-for-sale Securities, Portfolio Concentration Not Rated, Amortized Cost	[11]	5,577,287						5,577,287				5,577,287
Available-for-sale Securities, Portfolio Concentration Not Rated, Fair Value	[11]	5,700,268						5,700,268				5,700,268
U.S. government agency residential mortgage-backed securities [Member] | Federal National Mortgage Association Certificates and Obligations (FNMA) [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost		2,908,698		3,156,214		3,558,224		2,908,698		3,558,224		2,908,698
Available-for-sale Securities, Fair Value		2,988,974		3,187,215		3,609,273		2,988,974		3,609,273		2,988,974
Available-for-sale Securities, Gross Unrealized Gain		80,549	[1]	41,502	[2]	57,269	[3]	80,549	[1]	57,269	[3]	80,549	[1]
Available-for-sale Securities, Gross Unrealized Loss		(273)	[1]	(10,501)	[2]	(6,220)	[3]	(273)	[1]	(6,220)	[3]	(273)	[1]
Available-for-Sale Securities, Other Than Temporary Impairments		0	[4]	0	[5]	0	[6]	0	[4]	0	[6]	0	[4]
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Amortized Cost		2,908,698		3,156,214		3,558,224		2,908,698		3,558,224		2,908,698
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Fair Value		$ 2,988,974		$ 3,187,215		$ 3,609,273		$ 2,988,974		$ 3,609,273		$ 2,988,974
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions		4		55		29		4		29		4
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		$ 97,910		$ 1,188,022		$ 601,863		$ 97,910		$ 601,863		$ 97,910
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		15,401		18,236		118,269		15,401		118,269		15,401
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		113,311		1,206,258		720,132		113,311		720,132		113,311
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		267		10,262		4,327		267		4,327		267
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		6		239		1,893		6		1,893		6
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		273		10,501		6,220		273		6,220		273
U.S. government agency residential mortgage-backed securities [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		1,746,661		1,940,915		1,929,685		1,746,661		1,929,685		1,746,661
Available-for-sale Securities, Fair Value		1,785,332		1,949,335		1,954,917		1,785,332		1,954,917		1,785,332
Available-for-sale Securities, Gross Unrealized Gain		38,869	[1]	14,727	[2]	27,594	[3]	38,869	[1]	27,594	[3]	38,869	[1]
Available-for-sale Securities, Gross Unrealized Loss		(198)	[1]	(6,307)	[2]	(2,362)	[3]	(198)	[1]	(2,362)	[3]	(198)	[1]
Available-for-Sale Securities, Other Than Temporary Impairments		0	[4]	0	[5]	0	[6]	0	[4]	0	[6]	0	[4]
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Amortized Cost		1,746,661		1,940,915		1,929,685		1,746,661		1,929,685		1,746,661
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Fair Value		$ 1,785,332		$ 1,949,335		$ 1,954,917		$ 1,785,332		$ 1,954,917		$ 1,785,332
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions		1		40		13		1		13		1
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		$ 726,713		$ 121,217		$ 0		$ 121,217		$ 0
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		22,338		77,545		117,408		22,338		117,408		22,338
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		22,338		804,258		238,625		22,338		238,625		22,338
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		0		4,827		795		0		795		0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		198		1,480		1,567		198		1,567		198
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		198		6,307		2,362		198		2,362		198
U.S. government agency residential mortgage-backed securities [Member] | Government National Mortgage Association Certificates and Obligations (GNMA) [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost		921,928		763,967		768,342		921,928		768,342		921,928
Available-for-sale Securities, Fair Value		925,962		761,801		770,739		925,962		770,739		925,962
Available-for-sale Securities, Gross Unrealized Gain		4,646	[1]	2,385	[2]	4,928	[3]	4,646	[1]	4,928	[3]	4,646	[1]
Available-for-sale Securities, Gross Unrealized Loss		(612)	[1]	(4,551)	[2]	(2,531)	[3]	(612)	[1]	(2,531)	[3]	(612)	[1]
Available-for-Sale Securities, Other Than Temporary Impairments		0	[4]	0	[5]	0	[6]	0	[4]	0	[6]	0	[4]
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Amortized Cost		921,928		763,967		768,342		921,928		768,342		921,928
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Fair Value		$ 925,962		$ 761,801		$ 770,739		$ 925,962		$ 770,739		$ 925,962
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		15		6		11		6		11
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		$ 349,631		$ 364,919		$ 66,131		$ 349,631		$ 66,131		$ 349,631
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		0		102,109		115,103		0		115,103		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		349,631		467,028		181,234		349,631		181,234		349,631
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		612		1,951		50		612		50		612
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		0		2,600		2,481		0		2,481		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		612		4,551		2,531		612		2,531		612
U.S. government agency residential mortgage-backed securities [Member] | Other [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost		0		0		4,224		0		4,224		0
Available-for-sale Securities, Fair Value		0		0		4,520		0		4,520		0
Available-for-sale Securities, Gross Unrealized Gain		0	[1]	0	[2]	296	[3]	0	[1]	296	[3]	0	[1]
Available-for-sale Securities, Gross Unrealized Loss		0	[1]	0	[2]	0	[3]	0	[1]	0	[3]	0	[1]
Available-for-Sale Securities, Other Than Temporary Impairments		0	[4]	0	[5]	0	[6]	0	[4]	0	[6]	0	[4]
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Amortized Cost		0		0		4,224		0		4,224		0
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Fair Value		0		0		4,520		0		4,520		0
Privately issued residential mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost		115,309		128,111		142,454		115,309		142,454		115,309
Available-for-sale Securities, Fair Value		126,313		139,118		154,150		126,313		154,150		126,313
Available-for-sale Securities, Gross Unrealized Gain		11,816	[1]	11,834	[2]	12,535	[3]	11,816	[1]	12,535	[3]	11,816	[1]
Available-for-sale Securities, Gross Unrealized Loss		(36)	[1]	0	[2]	0	[3]	(36)	[1]	0	[3]	(36)	[1]
Available-for-Sale Securities, Other Than Temporary Impairments		(776)	[4]	(827)	[5]	(839)	[6]	(776)	[4]	(839)	[6]	(776)	[4]
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Amortized Cost		115,309		128,111		142,454		115,309		142,454		115,309
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Fair Value		$ 126,313		$ 139,118		$ 154,150		$ 126,313		$ 154,150		$ 126,313
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions		14	[12]	12	[13]	15	[14]	14	[12]	15	[14]	14	[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		$ 15,589	[12]	$ 0	[13]	$ 17,786	[14]	$ 15,589	[12]	$ 17,786	[14]	$ 15,589	[12]
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		16,168	[12]	17,746	[13]	9,310	[14]	16,168	[12]	9,310	[14]	16,168	[12]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		31,757	[12]	17,746	[13]	27,096	[14]	31,757	[12]	27,096	[14]	31,757	[12]
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		277	[12]	0	[13]	485	[14]	277	[12]	485	[14]	277	[12]
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		535	[12]	827	[13]	354	[14]	535	[12]	354	[14]	535	[12]
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		812	[12]	$ 827	[13]	$ 839	[14]	812	[12]	839	[14]	812	[12]
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 Rated AAA To AA, Amortized Cost		0						0				0
Available-for-sale Securities, Portfolio Concentration Rated AAA To AA, Fair Value		0						0				0
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Amortized Cost		0						0				0
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Fair Value		0						0				0
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Amortized Cost		115,309						115,309				115,309
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value		126,313						126,313				126,313
Available-for-sale Securities, Portfolio Concentration Not Rated, Amortized Cost		0						0				0
Available-for-sale Securities, Portfolio Concentration Not Rated, Fair Value		$ 0						$ 0				$ 0
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]
Unemployment rate		Moving down to 4.7 percent over the next 12 months and remain at 4.7 percent thereafter.		Decreasing to 4.8 percent over the next 12 months and remain at 4.8 percent thereafter.		Held constant at 5.6 percent over the next 12 months and remain at 5.6 percent thereafter.
Housing price appreciation/depreciation	[15]	Starting with current depreciated housing prices based on information derived from the FHFA1, appreciating 3.5 percent over the next 12 months, then flat for the following 12 months and then appreciating at 2 percent per year thereafter.		Starting with current depreciated housing prices based on information derived from the FHFA1, appreciating 3.5 percent over the next 12 months, then flat for the following 12 months and then appreciating at 2 percent per year thereafter.		Starting with current depreciated housing prices based on information derived from the FHFA1, appreciating 3.2 percent over the next 12 months, then flat for the following 12 months and then appreciating at 2 percent per year thereafter.
Estimated liquidation costs		Reflect actual historical liquidations costs observed on Jumbo and Alt-A residential mortgage loans in securities owned by the Company.		Reflect actual historical liquidations costs observed on Jumbo and Alt-A residential mortgage loans in securities owned by the Company.		Reflect actual historical liquidations costs observed on Jumbo and Alt-A residential mortgage loans in securities owned by the Company.
Discount rates		Estimated cash flows were discounted at rates that range from 2.00 percent to 6.25 percent based on our current expected yields.		Estimated cash flows were discounted at rates that range from 2.00 percent to 6.25 percent based on our current expected yields.		Estimated cash flows were discounted at rates that range from 2.00 percent to 6.25 percent based on our current expected yields.
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		44						44				44
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		0										43
Amount of Credit Losses Recognized in Current Period		$ 0										$ 54,504
Privately issued residential mortgage-backed securities [Member] | Alt A loans Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost		49,522		$ 56,387		$ 61,486		$ 49,522		61,486		49,522
Available-for-sale Securities, Fair Value		54,536		62,574		67,711		54,536		67,711		54,536
Available-for-sale Securities, Gross Unrealized Gain		5,461	[1]	6,574	[2]	6,692	[3]	5,461	[1]	6,692	[3]	5,461	[1]
Available-for-sale Securities, Gross Unrealized Loss		0	[1]	0	[2]	0	[3]	0	[1]	0	[3]	0	[1]
Available-for-Sale Securities, Other Than Temporary Impairments		(447)	[4]	(387)	[5]	(467)	[6]	(447)	[4]	(467)	[6]	(447)	[4]
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Amortized Cost		49,522		56,387		61,486		49,522		61,486		49,522
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Fair Value		$ 54,536		$ 62,574		$ 67,711		$ 54,536		$ 67,711		$ 54,536
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions		5	[12]	4	[13]	4	[14]	5	[12]	4	[14]	5	[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		$ 8,513	[12]	$ 0	[13]	$ 10,244	[14]	$ 8,513	[12]	$ 10,244	[14]	$ 8,513	[12]
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		8,291	[12]	9,264	[13]	0	[14]	8,291	[12]	0	[14]	8,291	[12]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		16,804	[12]	9,264	[13]	10,244	[14]	16,804	[12]	10,244	[14]	16,804	[12]
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		241	[12]	0	[13]	467	[14]	241	[12]	467	[14]	241	[12]
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		206	[12]	387	[13]	0	[14]	206	[12]	0	[14]	206	[12]
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		$ 447	[12]	387	[13]	467	[14]	$ 447	[12]	467	[14]	$ 447	[12]
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		14						14				14
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		0										14
Amount of Credit Losses Recognized in Current Period		$ 0										$ 36,284
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		65,787		71,724		80,968		$ 65,787		80,968		65,787
Available-for-sale Securities, Fair Value		71,777		76,544		86,439		71,777		86,439		71,777
Available-for-sale Securities, Gross Unrealized Gain		6,355	[1]	5,260	[2]	5,843	[3]	6,355	[1]	5,843	[3]	6,355	[1]
Available-for-sale Securities, Gross Unrealized Loss		(36)	[1]	0	[2]	0	[3]	(36)	[1]	0	[3]	(36)	[1]
Available-for-Sale Securities, Other Than Temporary Impairments		(329)	[4]	(440)	[5]	(372)	[6]	(329)	[4]	(372)	[6]	(329)	[4]
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Amortized Cost		65,787		71,724		80,968		65,787		80,968		65,787
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Fair Value		$ 71,777		$ 76,544		$ 86,439		$ 71,777		$ 86,439		$ 71,777
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions		9	[12]	8	[13]	11	[14]	9	[12]	11	[14]	9	[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		$ 7,076	[12]	$ 0	[13]	$ 7,542	[14]	$ 7,076	[12]	$ 7,542	[14]	$ 7,076	[12]
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		7,877	[12]	8,482	[13]	9,310	[14]	7,877	[12]	9,310	[14]	7,877	[12]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		14,953	[12]	8,482	[13]	16,852	[14]	14,953	[12]	16,852	[14]	14,953	[12]
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		36	[12]	0	[13]	18	[14]	36	[12]	18	[14]	36	[12]
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		329	[12]	440	[13]	354	[14]	329	[12]	354	[14]	329	[12]
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		$ 365	[12]	440	[13]	372	[14]	$ 365	[12]	372	[14]	$ 365	[12]
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		30						30				30
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		0										29
Amount of Credit Losses Recognized in Current Period		$ 0										$ 18,220
Perpetual Preferred, Equity Securities and Mutual Funds [Member]
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Amortized Cost Basis		32,832						$ 32,832				32,832
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Fair Value		$ 36,745						$ 36,745				$ 36,745
Available-for-sale Securities, Debt Maturities, Nominal Yield [Abstract]
Available-for-sale Securities, Debt Maturities, Nominal Yield		0.00%						0.00%				0.00%
Perpetual preferred stock [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost		$ 15,562		17,171		17,171		$ 15,562		17,171		$ 15,562
Available-for-sale Securities, Fair Value		17,931		19,672		19,648		17,931		19,648		17,931
Available-for-sale Securities, Gross Unrealized Gain		2,369	[1]	2,501	[2]	2,477	[3]	2,369	[1]	2,477	[3]	2,369	[1]
Available-for-sale Securities, Gross Unrealized Loss		0	[1]	0	[2]	0	[3]	0	[1]	0	[3]	0	[1]
Available-for-Sale Securities, Other Than Temporary Impairments		0	[4]	0	[5]	0	[6]	0	[4]	0	[6]	0	[4]
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Amortized Cost		15,562		17,171		17,171		15,562		17,171		15,562
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Fair Value		$ 17,931		$ 19,672		$ 19,648		$ 17,931		$ 19,648		$ 17,931
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		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		$ 0		$ 0		$ 0
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		0		0		0		0		0		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		0		0		0		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, Accumulated Loss		0		0		0		0		0		0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		0		0		0		0		0		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		0		0		0		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 Rated AAA To AA, Amortized Cost		0						0				0
Available-for-sale Securities, Portfolio Concentration Rated AAA To AA, Fair Value		0						0				0
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Amortized Cost		4,796						4,796				4,796
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Fair Value		5,543						5,543				5,543
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Amortized Cost		10,766						10,766				10,766
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value		12,388						12,388				12,388
Available-for-sale Securities, Portfolio Concentration Not Rated, Amortized Cost		0						0				0
Available-for-sale Securities, Portfolio Concentration Not Rated, Fair Value		0						0				0
Equity securities and mutual funds [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost		17,270		17,121		18,638		17,270		18,638		17,270
Available-for-sale Securities, Fair Value		18,814		17,833		18,732		18,814		18,732		18,814
Available-for-sale Securities, Gross Unrealized Gain		1,558	[1]	752	[2]	840	[3]	1,558	[1]	840	[3]	1,558	[1]
Available-for-sale Securities, Gross Unrealized Loss		(14)	[1]	(40)	[2]	(746)	[3]	(14)	[1]	(746)	[3]	(14)	[1]
Available-for-Sale Securities, Other Than Temporary Impairments		0	[4]	0	[5]	0	[6]	0	[4]	0	[6]	0	[4]
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Amortized Cost		17,270		17,121		18,638		17,270		18,638		17,270
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Fair Value		$ 18,814		$ 17,833		$ 18,732		$ 18,814		$ 18,732		$ 18,814
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions		30		61		51		30		51		30
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		$ 782		$ 4,706		$ 0		$ 4,706		$ 0
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		889		991		994		889		994		889
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		889		1,773		5,700		889		5,700		889
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Losses [Abstract]
Available-for-sale Securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss		0		5		714		0		714		0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		14		35		32		14		32		14
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		14		$ 40		$ 746		14		$ 746		14
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 Rated AAA To AA, Amortized Cost		4						4				4
Available-for-sale Securities, Portfolio Concentration Rated AAA To AA, Fair Value		492						492				492
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Amortized Cost		0						0				0
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Fair Value		0						0				0
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Amortized Cost		0						0				0
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value		0						0				0
Available-for-sale Securities, Portfolio Concentration Not Rated, Amortized Cost		17,266						17,266				17,266
Available-for-sale Securities, Portfolio Concentration Not Rated, Fair Value		$ 18,322						$ 18,322				$ 18,322

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

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

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

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

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

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

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

[8] Calculated on a taxable equivalent basis using a 39 percent effective tax rate.

[9] 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.

[10] 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. See Quarterly Financial Summary –– Unaudited following for current yields on available for sale securities portfolio.

[11] 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.

[12] Includes securities for which an unrealized loss remains in AOCI after an other-than-temporary credit loss has been recognized in income.

[13] Includes securities for which an unrealized loss remains in AOCI after an other-than-temporary credit loss has been recognized in income.

[14] Includes securities for which an unrealized loss remains in AOCI after an other-than-temporary credit loss has been recognized in income.

[15] Federal Housing Finance Agency