Available for Sale Securities (Details) $ in Thousands		3 Months Ended						9 Months Ended				93 Months Ended
		Sep. 30, 2016 USD ($)		Dec. 31, 2015 USD ($)		Sep. 30, 2015 USD ($)		Sep. 30, 2016 USD ($)		Sep. 30, 2015 USD ($)		Sep. 30, 2016 USD ($)
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost		$ 8,702,750		$ 9,004,624		$ 8,656,205		$ 8,702,750		$ 8,656,205		$ 8,702,750
Available-for-sale Securities, Fair Value		8,862,283		9,042,733		8,801,089		8,862,283		8,801,089		8,862,283
Available-for-sale Securities, Gross Unrealized Gain		165,765	[1]	79,970	[2]	152,797	[3]	165,765	[1]	152,797	[3]	165,765	[1]
Available-for-sale Securities, Gross Unrealized Loss		(6,028)	[1]	(41,034)	[2]	(6,896)	[3]	(6,028)	[1]	(6,896)	[3]	(6,028)	[1]
Available-for-Sale Securities, Other Than Temporary Impairments		(204)	[4]	(827)	[5]	(1,017)	[6]	(204)	[4]	(1,017)	[6]	(204)	[4]
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Amortized Cost		8,702,750		9,004,624		8,656,205		8,702,750		8,656,205		8,702,750
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Fair Value		$ 8,862,283		9,042,733		8,801,089		$ 8,862,283		8,801,089		$ 8,862,283
Available-for-sale Securities, Debt Maturities, Nominal Yield [Abstract]
Available-for-sale Securities, Debt Maturities, Nominal Yield		1.84%						1.84%				1.84%
Available-for-sale Securities, Gross Realized Gain (Loss), Disclosures [Abstract]
Available-for-sale Securities, Proceeds		$ 232,239				450,765		$ 1,027,379		1,164,425
Available-for-sale Securities, Gross realized gains		2,415				3,803		11,705		13,543
Available-for-sale Securities, Gross realized losses		(21)				(1,637)		(21)		(3,617)
Available-for-sale Securities, Related federal and state income tax expense		931				843		4,545		3,861
Available-for-sale Securities, Pledged as Collateral [Abstract]
Available-for-sale Securities, Pledged As Collateral, Amortized cost		7,098,721		6,831,743		6,225,689		7,098,721		6,225,689		$ 7,098,721
Available-for-sale Securities, Pledged As Collateral, Fair value		$ 7,213,520		$ 6,849,524		$ 6,318,330		$ 7,213,520		$ 6,318,330		$ 7,213,520
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions		130		419		115		130		115		130
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		$ 1,107,872		$ 3,873,809		$ 632,216		$ 1,107,872		$ 632,216		$ 1,107,872
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		327,297		716,700		323,379		327,297		323,379		327,297
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		1,435,169		4,590,509		955,595		1,435,169		955,595		1,435,169
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		4,786		28,496		5,400		4,786		5,400		4,786
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		1,446		13,365		2,513		1,446		2,513		1,446
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		6,232		41,861		7,913		6,232		7,913		6,232
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		28,241						28,241				28,241
Available-for-sale Securities, Portfolio Concentration Rated AAA To AA, Fair Value		29,032						29,032				29,032
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Amortized Cost		10,471						10,471				10,471
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Fair Value		10,821						10,821				10,821
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Amortized Cost		119,182						119,182				119,182
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value		135,676						135,676				135,676
Available-for-sale Securities, Portfolio Concentration Not Rated, Amortized Cost		8,544,856						8,544,856				8,544,856
Available-for-sale Securities, Portfolio Concentration Not Rated, Fair Value		8,686,754						8,686,754				8,686,754
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		9,089						9,089				9,089
Available-for-sale Securities, Debt Maturities, One to Five Years, Amortized Cost Basis		946,354						946,354				946,354
Available-for-sale Securities, Debt Maturities, Six To Ten Years, Amortized Cost Basis		1,819,258						1,819,258				1,819,258
Available-for-sale Securities, Debt Maturities, Over Ten Years, Amortized Cost Basis		215,630						215,630				215,630
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis		2,990,331						2,990,331				2,990,331
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Less than One Year, Fair Value		9,190						9,190				9,190
Available-for-sale Securities, Debt Maturities, One to Five Years, Fair Value		957,854						957,854				957,854
Available-for-sale Securities, Debt Maturities, Six to Ten Years, Fair Value		1,850,571						1,850,571				1,850,571
Available-for-sale Securities, Debt Maturities, Over Ten Years, Fair Value		216,125						216,125				216,125
Available-for-sale Securities, Debt Maturities, Single Maturity Date		$ 3,033,740						$ 3,033,740				$ 3,033,740
Available-for-sale Securities, Debt Maturities, Nominal Yield [Abstract]
Available-for-sale Securities, Debt Maturities, Less than One Year, Nominal Yield		4.97%						4.97%				4.97%
Available-for-sale Securities, Debt Maturities, One to Five Years, Nominal Yield		1.77%						1.77%				1.77%
Available-for-sale Securities, Debt Maturities, Six To Ten Years, Nominal Yield		1.85%						1.85%				1.85%
Available-for-sale Securities, Debt Maturities, Over Ten Years, Nominal Yield		1.61%						1.61%				1.61%
Available-for-sale Securities, Debt Maturities, Nominal Yield		1.81%						1.81%				1.81%
Available-for-sale Securities, Debt Maturities, Weighted Average Maturity	[7]	6.87						6.87				6.87
U.S. Treasury
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		1,002		995		1,003		1,002		1,003		1,002
Available-for-sale Securities, Gross Unrealized Gain		2	[1]	0	[2]	3	[3]	2	[1]	3	[3]	2	[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		1,002						1,002				1,002
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		1,002						1,002				1,002
Available-for-sale Securities, Debt Maturities, Fair Value		$ 1,002		$ 995		1,003		$ 1,002		1,003		$ 1,002
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]	1.29						1.29				1.29
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		1,002						1,002				1,002
Municipal and other tax-exempt securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost		41,943		56,681		57,610		41,943		57,610		41,943
Available-for-sale Securities, Fair Value		42,092		56,817		57,960		42,092		57,960		42,092
Available-for-sale Securities, Gross Unrealized Gain		602	[1]	873	[2]	1,065	[3]	602	[1]	1,065	[3]	602	[1]
Available-for-sale Securities, Gross Unrealized Loss		(453)	[1]	(737)	[2]	(715)	[3]	(453)	[1]	(715)	[3]	(453)	[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		9,089						9,089				9,089
Available-for-sale Securities, Debt Maturities, One to Five Years, Amortized Cost Basis		13,593						13,593				13,593
Available-for-sale Securities, Debt Maturities, Six To Ten Years, Amortized Cost Basis		2,092						2,092				2,092
Available-for-sale Securities, Debt Maturities, Over Ten Years, Amortized Cost Basis		17,169						17,169				17,169
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis		41,943						41,943				41,943
Available-for-sale Securities, Debt Maturities, Amortized Cost		41,943		56,681		57,610		41,943		57,610		41,943
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Less than One Year, Fair Value		9,190						9,190				9,190
Available-for-sale Securities, Debt Maturities, One to Five Years, Fair Value		13,858						13,858				13,858
Available-for-sale Securities, Debt Maturities, Six to Ten Years, Fair Value		2,109						2,109				2,109
Available-for-sale Securities, Debt Maturities, Over Ten Years, Fair Value		16,935						16,935				16,935
Available-for-sale Securities, Debt Maturities, Single Maturity Date		42,092						42,092				42,092
Available-for-sale Securities, Debt Maturities, Fair Value		$ 42,092		$ 56,817		$ 57,960		$ 42,092		$ 57,960		$ 42,092
Available-for-sale Securities, Debt Maturities, Nominal Yield [Abstract]
Available-for-sale Securities, Debt Maturities, Less than One Year, Nominal Yield	[8]	4.97%						4.97%				4.97%
Available-for-sale Securities, Debt Maturities, One to Five Years, Nominal Yield	[8]	3.85%						3.85%				3.85%
Available-for-sale Securities, Debt Maturities, Six To Ten Years, Nominal Yield	[8]	3.46%						3.46%				3.46%
Available-for-sale Securities, Debt Maturities, Over Ten Years, Nominal Yield	[8],[9]	2.36%						2.36%				2.36%
Available-for-sale Securities, Debt Maturities, Nominal Yield	[8]	3.46%						3.46%				3.46%
Available-for-sale Securities, Debt Maturities, Weighted Average Maturity	[7]	8.14						8.14				8.14
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		20		20		18		20		18		20
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		$ 2,210		$ 9,909		$ 7,868		$ 2,210		$ 7,868		$ 2,210
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		6,396		11,664		3,800		6,396		3,800		6,396
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		8,606		21,573		11,668		8,606		11,668		8,606
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		3		27		485		3		485		3
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		450		710		230		450		230		450
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		453		737		715		453		715		453
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		23,837						23,837				23,837
Available-for-sale Securities, Portfolio Concentration Rated AAA To AA, Fair Value		24,290						24,290				24,290
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Amortized Cost		5,675						5,675				5,675
Available-for-sale Securities, Portfolio Concentration Rated A To BBB, Fair Value		5,316						5,316				5,316
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		12,431						12,431				12,431
Available-for-sale Securities, Portfolio Concentration Not Rated, Fair Value		12,486						12,486				12,486
Commercial mortgage-backed securities guaranteed by U.S. government agencies
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost		2,942,988		2,919,044		2,708,931		2,942,988		2,708,931		2,942,988
Available-for-sale Securities, Fair Value		2,986,495		2,905,796		2,735,787		2,986,495		2,735,787		2,986,495
Available-for-sale Securities, Gross Unrealized Gain		45,329	[1]	5,396	[2]	28,889	[3]	45,329	[1]	28,889	[3]	45,329	[1]
Available-for-sale Securities, Gross Unrealized Loss		(1,822)	[1]	(18,644)	[2]	(2,033)	[3]	(1,822)	[1]	(2,033)	[3]	(1,822)	[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		931,761						931,761				931,761
Available-for-sale Securities, Debt Maturities, Six To Ten Years, Amortized Cost Basis		1,817,166						1,817,166				1,817,166
Available-for-sale Securities, Debt Maturities, Over Ten Years, Amortized Cost Basis		194,061						194,061				194,061
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis		2,942,988						2,942,988				2,942,988
Available-for-sale Securities, Debt Maturities, Amortized Cost		2,942,988		2,919,044		2,708,931		2,942,988		2,708,931		2,942,988
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		942,994						942,994				942,994
Available-for-sale Securities, Debt Maturities, Six to Ten Years, Fair Value		1,848,462						1,848,462				1,848,462
Available-for-sale Securities, Debt Maturities, Over Ten Years, Fair Value		195,039						195,039				195,039
Available-for-sale Securities, Debt Maturities, Single Maturity Date		2,986,495						2,986,495				2,986,495
Available-for-sale Securities, Debt Maturities, Fair Value		$ 2,986,495		$ 2,905,796		$ 2,735,787		$ 2,986,495		$ 2,735,787		$ 2,986,495
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		1.74%						1.74%				1.74%
Available-for-sale Securities, Debt Maturities, Six To Ten Years, Nominal Yield		1.84%						1.84%				1.84%
Available-for-sale Securities, Debt Maturities, Over Ten Years, Nominal Yield		1.54%						1.54%				1.54%
Available-for-sale Securities, Debt Maturities, Nominal Yield		1.79%						1.79%				1.79%
Available-for-sale Securities, Debt Maturities, Weighted Average Maturity	[7]	6.82						6.82				6.82
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions		33		213		31		33		31		33
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		$ 372,805		$ 1,582,469		$ 327,790		$ 372,805		$ 327,790		$ 372,805
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		60,851		484,258		223,007		60,851		223,007		60,851
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		433,656		2,066,727		550,797		433,656		550,797		433,656
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		1,656		11,419		1,488		1,656		1,488		1,656
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		166		7,225		545		166		545		166
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		1,822		18,644		2,033		1,822		2,033		1,822
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		2,942,988						2,942,988				2,942,988
Available-for-sale Securities, Portfolio Concentration Not Rated, Fair Value		2,986,495						2,986,495				2,986,495
Other debt securities
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		1.71%						1.71%				1.71%
Available-for-sale Securities, Debt Maturities, Weighted Average Maturity	[7]	30.91						30.91				30.91
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions		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		5,679,520		5,989,207		5,848,382		5,679,520		5,848,382		5,679,520
Available-for-sale Securities, Fair Value		5,790,275		6,037,469		5,964,809		5,790,275		5,964,809		5,790,275
Available-for-sale Securities, Gross Unrealized Gain		114,446	[1]	70,448	[2]	119,860	[3]	114,446	[1]	119,860	[3]	114,446	[1]
Available-for-sale Securities, Gross Unrealized Loss		(3,487)	[1]	(21,359)	[2]	(2,416)	[3]	(3,487)	[1]	(2,416)	[3]	(3,487)	[1]
Available-for-Sale Securities, Other Than Temporary Impairments		(204)	[4]	(827)	[5]	(1,017)	[6]	(204)	[4]	(1,017)	[6]	(204)	[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		5,679,520						5,679,520				5,679,520
Available-for-sale Securities, Debt Maturities, Amortized Cost		5,679,520		5,989,207		5,848,382		5,679,520		5,848,382		5,679,520
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Fair Value		5,790,275						5,790,275				5,790,275
Available-for-sale Securities, Debt Maturities, Fair Value		$ 5,790,275		$ 6,037,469		$ 5,964,809		$ 5,790,275		$ 5,964,809		$ 5,790,275
Available-for-sale Securities, Debt Maturities, Nominal Yield [Abstract]
Available-for-sale Securities, Debt Maturities, Nominal Yield	[10]	1.87%						1.87%				1.87%
Available-for-sale Securities, Debt Maturities, Average Expected Life of Mortgage-backed Securities								3 years 164 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		42		122		26		42		26		42
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		$ 732,771		$ 2,279,654		$ 290,615		$ 732,771		$ 290,615		$ 732,771
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		255,013		215,636		91,897		255,013		91,897		255,013
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		987,784		2,495,290		382,512		987,784		382,512		987,784
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		3,127		17,040		1,957		3,127		1,957		3,127
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		564		5,146		1,476		564		1,476		564
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		3,691		22,186		3,433		3,691		3,433		3,691
U.S. government agency residential mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost		5,571,104	[11]	5,861,096		5,714,323		5,571,104	[11]	5,714,323		5,571,104	[11]
Available-for-sale Securities, Fair Value		5,668,672	[11]	5,898,351		5,819,127		5,668,672	[11]	5,819,127		5,668,672	[11]
Available-for-sale Securities, Gross Unrealized Gain		101,029	[1]	58,614	[2]	107,220	[3]	101,029	[1]	107,220	[3]	101,029	[1]
Available-for-sale Securities, Gross Unrealized Loss		(3,461)	[1]	(21,359)	[2]	(2,416)	[3]	(3,461)	[1]	(2,416)	[3]	(3,461)	[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		5,571,104	[11]	5,861,096		5,714,323		5,571,104	[11]	5,714,323		5,571,104	[11]
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Fair Value		$ 5,668,672	[11]	$ 5,898,351		$ 5,819,127		$ 5,668,672	[11]	$ 5,819,127		$ 5,668,672	[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		36		110		14		36		14		36
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		$ 717,957		$ 2,279,654		$ 282,378		$ 717,957		$ 282,378		$ 717,957
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		247,240		197,890		81,549		247,240		81,549		247,240
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		965,197		2,477,544		363,927		965,197		363,927		965,197
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		2,960		17,040		1,535		2,960		1,535		2,960
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		501		4,319		881		501		881		501
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		3,461		21,359		2,416		3,461		2,416		3,461
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]	5,571,104						5,571,104				5,571,104
Available-for-sale Securities, Portfolio Concentration Not Rated, Fair Value	[11]	5,668,672						5,668,672				5,668,672
U.S. government agency residential mortgage-backed securities | Federal National Mortgage Association Certificates and Obligations (FNMA) [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost		3,035,041		3,156,214		3,115,810		3,035,041		3,115,810		3,035,041
Available-for-sale Securities, Fair Value		3,101,136		3,187,215		3,185,097		3,101,136		3,185,097		3,101,136
Available-for-sale Securities, Gross Unrealized Gain		67,859	[1]	41,502	[2]	69,757	[3]	67,859	[1]	69,757	[3]	67,859	[1]
Available-for-sale Securities, Gross Unrealized Loss		(1,764)	[1]	(10,501)	[2]	(470)	[3]	(1,764)	[1]	(470)	[3]	(1,764)	[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		3,035,041		3,156,214		3,115,810		3,035,041		3,115,810		3,035,041
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Fair Value		$ 3,101,136		$ 3,187,215		$ 3,185,097		$ 3,101,136		$ 3,185,097		$ 3,101,136
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		55		6		14		6		14
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		$ 365,201		$ 1,188,022		$ 155,747		$ 365,201		$ 155,747		$ 365,201
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		14,229		18,236		0		14,229		0		14,229
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		379,430		1,206,258		155,747		379,430		155,747		379,430
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		1,712		10,262		470		1,712		470		1,712
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		52		239		0		52		0		52
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		1,764		10,501		470		1,764		470		1,764
U.S. government agency residential mortgage-backed securities | Federal Home Loan Mortgage Corporation Certificates and Obligations (FHLMC) [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost		1,611,887		1,940,915		1,853,379		1,611,887		1,853,379		1,611,887
Available-for-sale Securities, Fair Value		1,641,178		1,949,335		1,885,201		1,641,178		1,885,201		1,641,178
Available-for-sale Securities, Gross Unrealized Gain		29,640	[1]	14,727	[2]	32,646	[3]	29,640	[1]	32,646	[3]	29,640	[1]
Available-for-sale Securities, Gross Unrealized Loss		(349)	[1]	(6,307)	[2]	(824)	[3]	(349)	[1]	(824)	[3]	(349)	[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		1,611,887		1,940,915		1,853,379		1,611,887		1,853,379		1,611,887
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Fair Value		$ 1,641,178		$ 1,949,335		$ 1,885,201		$ 1,641,178		$ 1,885,201		$ 1,641,178
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions		6		40		4		6		4		6
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		$ 122,713		$ 726,713		$ 71,930		$ 122,713		$ 71,930		$ 122,713
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		20,306		77,545		26,848		20,306		26,848		20,306
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		143,019		804,258		98,778		143,019		98,778		143,019
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		91		4,827		503		91		503		91
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		258		1,480		321		258		321		258
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		349		6,307		824		349		824		349
U.S. government agency residential mortgage-backed securities | Government National Mortgage Association Certificates and Obligations (GNMA) [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost		924,176		763,967		741,212		924,176		741,212		924,176
Available-for-sale Securities, Fair Value		926,358		761,801		744,647		926,358		744,647		926,358
Available-for-sale Securities, Gross Unrealized Gain		3,530	[1]	2,385	[2]	4,557	[3]	3,530	[1]	4,557	[3]	3,530	[1]
Available-for-sale Securities, Gross Unrealized Loss		(1,348)	[1]	(4,551)	[2]	(1,122)	[3]	(1,348)	[1]	(1,122)	[3]	(1,348)	[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		924,176		763,967		741,212		924,176		741,212		924,176
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Fair Value		$ 926,358		$ 761,801		$ 744,647		$ 926,358		$ 744,647		$ 926,358
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		15		4		16		4		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		$ 230,043		$ 364,919		$ 54,701		$ 230,043		$ 54,701		$ 230,043
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		212,705		102,109		54,701		212,705		54,701		212,705
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		442,748		467,028		109,402		442,748		109,402		442,748
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		1,157		1,951		562		1,157		562		1,157
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		191		2,600		560		191		560		191
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		1,348		4,551		1,122		1,348		1,122		1,348
U.S. government agency residential mortgage-backed securities | Other [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost		0		0		3,922		0		3,922		0
Available-for-sale Securities, Fair Value		0		0		4,182		0		4,182		0
Available-for-sale Securities, Gross Unrealized Gain		0	[1]	0	[2]	260	[3]	0	[1]	260	[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		3,922		0		3,922		0
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Fair Value		0		0		4,182		0		4,182		0
Privately issued residential mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost		108,416		128,111		134,059		108,416		134,059		108,416
Available-for-sale Securities, Fair Value		121,603		139,118		145,682		121,603		145,682		121,603
Available-for-sale Securities, Gross Unrealized Gain		13,417	[1]	11,834	[2]	12,640	[3]	13,417	[1]	12,640	[3]	13,417	[1]
Available-for-sale Securities, Gross Unrealized Loss		(26)	[1]	0	[2]	0	[3]	(26)	[1]	0	[3]	(26)	[1]
Available-for-Sale Securities, Other Than Temporary Impairments		(204)	[4]	(827)	[5]	(1,017)	[6]	(204)	[4]	(1,017)	[6]	(204)	[4]
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Amortized Cost		108,416		128,111		134,059		108,416		134,059		108,416
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Fair Value		$ 121,603		$ 139,118		$ 145,682		$ 121,603		$ 145,682		$ 121,603
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions		6	[12]	12	[13]	12	[14]	6	[12]	12	[14]	6	[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		$ 14,814	[12]	$ 0	[13]	$ 8,237	[14]	$ 14,814	[12]	$ 8,237	[14]	$ 14,814	[12]
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		7,773	[12]	17,746	[13]	10,348	[14]	7,773	[12]	10,348	[14]	7,773	[12]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		22,587	[12]	17,746	[13]	18,585	[14]	22,587	[12]	18,585	[14]	22,587	[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		167	[12]	0	[13]	422	[14]	167	[12]	422	[14]	167	[12]
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		63	[12]	827	[13]	595	[14]	63	[12]	595	[14]	63	[12]
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		230	[12]	$ 827	[13]	$ 1,017	[14]	230	[12]	1,017	[14]	230	[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		108,416						108,416				108,416
Available-for-sale Securities, Portfolio Concentration Rated Below Investment Grade, Fair Value		121,603						121,603				121,603
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.		Moving down to 5.1 percent over the next 12 months and remain at 5.1 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 | Alt A loans Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost		47,039		$ 56,387		$ 58,801		$ 47,039		58,801		47,039
Available-for-sale Securities, Fair Value		54,065		62,574		64,700		54,065		64,700		54,065
Available-for-sale Securities, Gross Unrealized Gain		7,230	[1]	6,574	[2]	6,519	[3]	7,230	[1]	6,519	[3]	7,230	[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		(204)	[4]	(387)	[5]	(620)	[6]	(204)	[4]	(620)	[6]	(204)	[4]
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Amortized Cost		47,039		56,387		58,801		47,039		58,801		47,039
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Fair Value		$ 54,065		$ 62,574		$ 64,700		$ 54,065		$ 64,700		$ 54,065
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		$ 8,231	[12]	$ 0	[13]	$ 2,857	[14]	$ 8,231	[12]	$ 2,857	[14]	$ 8,231	[12]
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		7,773	[12]	9,264	[13]	6,667	[14]	7,773	[12]	6,667	[14]	7,773	[12]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		16,004	[12]	9,264	[13]	9,524	[14]	16,004	[12]	9,524	[14]	16,004	[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		141	[12]	0	[13]	186	[14]	141	[12]	186	[14]	141	[12]
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		63	[12]	387	[13]	434	[14]	63	[12]	434	[14]	63	[12]
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		$ 204	[12]	387	[13]	620	[14]	$ 204	[12]	620	[14]	$ 204	[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 | Jumbo A loans [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost		61,377		71,724		75,258		$ 61,377		75,258		61,377
Available-for-sale Securities, Fair Value		67,538		76,544		80,982		67,538		80,982		67,538
Available-for-sale Securities, Gross Unrealized Gain		6,187	[1]	5,260	[2]	6,121	[3]	6,187	[1]	6,121	[3]	6,187	[1]
Available-for-sale Securities, Gross Unrealized Loss		(26)	[1]	0	[2]	0	[3]	(26)	[1]	0	[3]	(26)	[1]
Available-for-Sale Securities, Other Than Temporary Impairments		0	[4]	(440)	[5]	(397)	[6]	0	[4]	(397)	[6]	0	[4]
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Amortized Cost		61,377		71,724		75,258		61,377		75,258		61,377
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Fair Value		$ 67,538		$ 76,544		$ 80,982		$ 67,538		$ 80,982		$ 67,538
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	[12]	8	[13]	8	[14]	1	[12]	8	[14]	1	[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		$ 6,583	[12]	$ 0	[13]	$ 5,380	[14]	$ 6,583	[12]	$ 5,380	[14]	$ 6,583	[12]
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		0	[12]	8,482	[13]	3,681	[14]	0	[12]	3,681	[14]	0	[12]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		6,583	[12]	8,482	[13]	9,061	[14]	6,583	[12]	9,061	[14]	6,583	[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		26	[12]	0	[13]	236	[14]	26	[12]	236	[14]	26	[12]
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		0	[12]	440	[13]	161	[14]	0	[12]	161	[14]	0	[12]
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		$ 26	[12]	440	[13]	397	[14]	$ 26	[12]	397	[14]	$ 26	[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		32,899						$ 32,899				32,899
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Fair Value		$ 38,268						$ 38,268				$ 38,268
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
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		19,578		19,672		19,163		19,578		19,163		19,578
Available-for-sale Securities, Gross Unrealized Gain		4,016	[1]	2,501	[2]	2,030	[3]	4,016	[1]	2,030	[3]	4,016	[1]
Available-for-sale Securities, Gross Unrealized Loss		0	[1]	0	[2]	(38)	[3]	0	[1]	(38)	[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		$ 19,578		$ 19,672		$ 19,163		$ 19,578		$ 19,163		$ 19,578
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		1		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		$ 0		$ 1,912		$ 0		$ 1,912		$ 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		1,912		0		1,912		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		38		0		38		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		38		0		38		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		5,505						5,505				5,505
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		14,073						14,073				14,073
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
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost		17,337		17,121		18,711		17,337		18,711		17,337
Available-for-sale Securities, Fair Value		18,690		17,833		18,217		18,690		18,217		18,690
Available-for-sale Securities, Gross Unrealized Gain		1,370	[1]	752	[2]	950	[3]	1,370	[1]	950	[3]	1,370	[1]
Available-for-sale Securities, Gross Unrealized Loss		(17)	[1]	(40)	[2]	(1,444)	[3]	(17)	[1]	(1,444)	[3]	(17)	[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		17,337		17,121		18,711		17,337		18,711		17,337
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Fair Value		$ 18,690		$ 17,833		$ 18,217		$ 18,690		$ 18,217		$ 18,690
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions		33		61		37		33		37		33
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		$ 86		$ 782		$ 4,031		$ 86		$ 4,031		$ 86
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		886		991		526		886		526		886
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		972		1,773		4,557		972		4,557		972
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		1,432		0		1,432		0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		17		35		12		17		12		17
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		17		$ 40		$ 1,444		17		$ 1,444		17
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		591						591				591
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		17,333						17,333				17,333
Available-for-sale Securities, Portfolio Concentration Not Rated, Fair Value		$ 18,099						$ 18,099				$ 18,099

[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