Available for Sale Securities (Details) $ in Thousands		3 Months Ended				6 Months Ended
		Jun. 30, 2017 USD ($)		Jun. 30, 2016 USD ($)		Jun. 30, 2017 USD ($)		Jun. 30, 2016 USD ($)		Dec. 31, 2016 USD ($)
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost		$ 8,325,000		$ 8,635,304		$ 8,325,000		$ 8,635,304		$ 8,691,728
Available-for-sale Securities, Fair Value		8,341,041		8,830,689		8,341,041		8,830,689		8,676,829
Available-for-sale Securities, Gross Unrealized Gain		65,740	[1]	198,378	[2]	65,740	[1]	198,378	[2]	60,165	[3]
Available-for-sale Securities, Gross Unrealized Loss		(49,699)	[1]	(2,217)	[2]	(49,699)	[1]	(2,217)	[2]	(74,846)	[3]
Available-for-Sale Securities, Other Than Temporary Impairments		0	[4]	(776)	[5]	0	[4]	(776)	[5]	(218)	[6]
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Amortized Cost		8,325,000		8,635,304		8,325,000		8,635,304		8,691,728
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Fair Value		$ 8,341,041		8,830,689		$ 8,341,041		8,830,689		8,676,829
Available-for-sale Securities, Debt Maturities, Nominal Yield [Abstract]
Available-for-sale Securities, Debt Maturities, Nominal Yield		1.90%				1.90%
Available-for-sale Securities, Gross Realized Gain (Loss), Disclosures [Abstract]
Available-for-sale Securities, Proceeds		$ 460,402		325,758		$ 700,412		795,140
Available-for-sale Securities, Gross realized gains		2,763		5,326		4,855		9,290
Available-for-sale Securities, Gross realized losses		(2,383)		0		(2,426)		0
Available-for-sale Securities, Related federal and state income tax expense		148		2,072		945		3,614
Available-for-sale Securities, Pledged as Collateral [Abstract]
Available-for-sale Securities, Pledged As Collateral, Amortized cost		6,327,666		7,502,361		6,327,666		7,502,361		7,353,116
Available-for-sale Securities, Pledged As Collateral, Fair value		$ 6,317,623		$ 7,657,916		$ 6,317,623		$ 7,657,916		$ 7,327,470
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions		367		90		367		90		488
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		$ 3,818,331		$ 567,460		$ 3,818,331		$ 567,460		$ 5,231,605
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		268,886		135,093		268,886		135,093		178,249
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		4,087,217		702,553		4,087,217		702,553		5,409,854
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		44,025		1,193		44,025		1,193		70,818
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		5,674		1,800		5,674		1,800		4,246
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		49,699		2,993		49,699		2,993		75,064
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		68,244				68,244
Available-for-sale Securities, Debt Maturities, One to Five Years, Amortized Cost Basis		886,839				886,839
Available-for-sale Securities, Debt Maturities, Six To Ten Years, Amortized Cost Basis		1,572,763				1,572,763
Available-for-sale Securities, Debt Maturities, Over Ten Years, Amortized Cost Basis		298,982				298,982
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis		2,826,828				2,826,828
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Less than One Year, Fair Value		68,166				68,166
Available-for-sale Securities, Debt Maturities, One to Five Years, Fair Value		885,783				885,783
Available-for-sale Securities, Debt Maturities, Six to Ten Years, Fair Value		1,569,813				1,569,813
Available-for-sale Securities, Debt Maturities, Over Ten Years, Fair Value		296,223				296,223
Available-for-sale Securities, Debt Maturities, Single Maturity Date		$ 2,819,985				$ 2,819,985
Available-for-sale Securities, Debt Maturities, Nominal Yield [Abstract]
Available-for-sale Securities, Debt Maturities, Less than One Year, Nominal Yield		1.60%				1.60%
Available-for-sale Securities, Debt Maturities, One to Five Years, Nominal Yield		1.85%				1.85%
Available-for-sale Securities, Debt Maturities, Six To Ten Years, Nominal Yield		1.85%				1.85%
Available-for-sale Securities, Debt Maturities, Over Ten Years, Nominal Yield		1.90%				1.90%
Available-for-sale Securities, Debt Maturities, Nominal Yield		1.83%				1.83%
Available-for-sale Securities, Debt Maturities, Weighted Average Maturity	[7]	7.03				7.03
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
Available-for-sale Securities, Fair Value		998		1,004		998		1,004		999
Available-for-sale Securities, Gross Unrealized Gain		0	[1]	4	[2]	0	[1]	4	[2]	0	[3]
Available-for-sale Securities, Gross Unrealized Loss		(2)	[1]	0	[2]	(2)	[1]	0	[2]	(1)	[3]
Available-for-Sale Securities, Other Than Temporary Impairments		0	[4]	0	[5]	0	[4]	0	[5]	0	[6]
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		1,000				1,000
Available-for-sale Securities, Debt Maturities, One to Five Years, Amortized Cost Basis		0				0
Available-for-sale Securities, Debt Maturities, Six To Ten Years, Amortized Cost Basis		0				0
Available-for-sale Securities, Debt Maturities, Over Ten Years, Amortized Cost Basis		0				0
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis		1,000				1,000
Available-for-sale Securities, Debt Maturities, Amortized Cost		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		998				998
Available-for-sale Securities, Debt Maturities, One to Five Years, Fair Value		0				0
Available-for-sale Securities, Debt Maturities, Six to Ten Years, Fair Value		0				0
Available-for-sale Securities, Debt Maturities, Over Ten Years, Fair Value		0				0
Available-for-sale Securities, Debt Maturities, Single Maturity Date		998				998
Available-for-sale Securities, Debt Maturities, Fair Value		$ 998		$ 1,004		$ 998		$ 1,004		$ 999
Available-for-sale Securities, Debt Maturities, Nominal Yield [Abstract]
Available-for-sale Securities, Debt Maturities, Less than One Year, Nominal Yield		0.87%				0.87%
Available-for-sale Securities, Debt Maturities, One to Five Years, Nominal Yield		0.00%				0.00%
Available-for-sale Securities, Debt Maturities, Six To Ten Years, Nominal Yield		0.00%				0.00%
Available-for-sale Securities, Debt Maturities, Over Ten Years, Nominal Yield		0.00%				0.00%
Available-for-sale Securities, Debt Maturities, Nominal Yield		0.87%				0.87%
Available-for-sale Securities, Debt Maturities, Weighted Average Maturity	[7]	0.55				0.55
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		0		1		0		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		$ 997		$ 0		$ 997		$ 0		$ 999
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		0		0		0		0		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		997		0		997		0		999
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		0		2		0		1
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		0		0		0		0		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		2		0		2		0		1
Municipal and other tax-exempt securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost		32,885		50,170		32,885		50,170		41,050
Available-for-sale Securities, Fair Value		32,765		50,262		32,765		50,262		40,993
Available-for-sale Securities, Gross Unrealized Gain		293	[1]	805	[2]	293	[1]	805	[2]	343	[3]
Available-for-sale Securities, Gross Unrealized Loss		(413)	[1]	(713)	[2]	(413)	[1]	(713)	[2]	(400)	[3]
Available-for-Sale Securities, Other Than Temporary Impairments		0	[4]	0	[5]	0	[4]	0	[5]	0	[6]
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		8,981				8,981
Available-for-sale Securities, Debt Maturities, One to Five Years, Amortized Cost Basis		6,380				6,380
Available-for-sale Securities, Debt Maturities, Six To Ten Years, Amortized Cost Basis		1,028				1,028
Available-for-sale Securities, Debt Maturities, Over Ten Years, Amortized Cost Basis		16,496				16,496
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis		32,885				32,885
Available-for-sale Securities, Debt Maturities, Amortized Cost		32,885		50,170		32,885		50,170		41,050
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Less than One Year, Fair Value		9,021				9,021
Available-for-sale Securities, Debt Maturities, One to Five Years, Fair Value		6,497				6,497
Available-for-sale Securities, Debt Maturities, Six to Ten Years, Fair Value		1,081				1,081
Available-for-sale Securities, Debt Maturities, Over Ten Years, Fair Value		16,166				16,166
Available-for-sale Securities, Debt Maturities, Single Maturity Date		32,765				32,765
Available-for-sale Securities, Debt Maturities, Fair Value		$ 32,765		$ 50,262		$ 32,765		$ 50,262		$ 40,993
Available-for-sale Securities, Debt Maturities, Nominal Yield [Abstract]
Available-for-sale Securities, Debt Maturities, Less than One Year, Nominal Yield	[8]	4.24%				4.24%
Available-for-sale Securities, Debt Maturities, One to Five Years, Nominal Yield	[8]	3.91%				3.91%
Available-for-sale Securities, Debt Maturities, Six To Ten Years, Nominal Yield	[8]	6.72%				6.72%
Available-for-sale Securities, Debt Maturities, Over Ten Years, Nominal Yield	[8],[9]	2.28%				2.28%
Available-for-sale Securities, Debt Maturities, Nominal Yield	[8]	3.27%				3.27%
Available-for-sale Securities, Debt Maturities, Weighted Average Maturity	[7]	8.87				8.87
Available-for-sale Securities, Debt Maturities, Effective tax rate for nominal yield calculation		39.00%				39.00%
Available-for-sale Securities, Debt Maturities, Number of days for interest rates to reset		35 days
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions		13		17		13		17		24
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		$ 1,957		$ 375		$ 1,957		$ 375		$ 15,666
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		4,655		10,289		4,655		10,289		4,689
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		6,612		10,664		6,612		10,664		20,355
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		0		1		0		22
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		412		713		412		713		378
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		413		713		413		713		400
Commercial mortgage-backed securities guaranteed by U.S. government agencies
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost		2,788,543		2,854,306		2,788,543		2,854,306		3,035,750
Available-for-sale Securities, Fair Value		2,782,070		2,911,946		2,782,070		2,911,946		3,017,933
Available-for-sale Securities, Gross Unrealized Gain		7,804	[1]	57,762	[2]	7,804	[1]	57,762	[2]	5,472	[3]
Available-for-sale Securities, Gross Unrealized Loss		(14,277)	[1]	(122)	[2]	(14,277)	[1]	(122)	[2]	(23,289)	[3]
Available-for-Sale Securities, Other Than Temporary Impairments		0	[4]	0	[5]	0	[4]	0	[5]	0	[6]
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		58,263				58,263
Available-for-sale Securities, Debt Maturities, One to Five Years, Amortized Cost Basis		880,459				880,459
Available-for-sale Securities, Debt Maturities, Six To Ten Years, Amortized Cost Basis		1,571,735				1,571,735
Available-for-sale Securities, Debt Maturities, Over Ten Years, Amortized Cost Basis		278,086				278,086
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis		2,788,543				2,788,543
Available-for-sale Securities, Debt Maturities, Amortized Cost		2,788,543		2,854,306		2,788,543		2,854,306		3,035,750
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Less than One Year, Fair Value		58,147				58,147
Available-for-sale Securities, Debt Maturities, One to Five Years, Fair Value		879,286				879,286
Available-for-sale Securities, Debt Maturities, Six to Ten Years, Fair Value		1,568,732				1,568,732
Available-for-sale Securities, Debt Maturities, Over Ten Years, Fair Value		275,905				275,905
Available-for-sale Securities, Debt Maturities, Single Maturity Date		2,782,070				2,782,070
Available-for-sale Securities, Debt Maturities, Fair Value		$ 2,782,070		$ 2,911,946		$ 2,782,070		$ 2,911,946		$ 3,017,933
Available-for-sale Securities, Debt Maturities, Nominal Yield [Abstract]
Available-for-sale Securities, Debt Maturities, Less than One Year, Nominal Yield		1.20%				1.20%
Available-for-sale Securities, Debt Maturities, One to Five Years, Nominal Yield		1.83%				1.83%
Available-for-sale Securities, Debt Maturities, Six To Ten Years, Nominal Yield		1.84%				1.84%
Available-for-sale Securities, Debt Maturities, Over Ten Years, Nominal Yield		1.88%				1.88%
Available-for-sale Securities, Debt Maturities, Nominal Yield		1.82%				1.82%
Available-for-sale Securities, Debt Maturities, Weighted Average Maturity	[7]	6.98				6.98
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions		121		11		121		11		171
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		$ 1,388,406		$ 103,955		$ 1,388,406		$ 103,955		$ 1,904,584
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		78,828		65,857		78,828		65,857		38,875
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		1,467,234		169,812		1,467,234		169,812		1,943,459
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		12,690		37		12,690		37		22,987
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		1,587		85		1,587		85		302
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		14,277		122		14,277		122		23,289
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
Available-for-sale Securities, Fair Value		4,152		4,151		4,152		4,151		4,152
Available-for-sale Securities, Gross Unrealized Gain		0	[1]	0	[2]	0	[1]	0	[2]	0	[3]
Available-for-sale Securities, Gross Unrealized Loss		(248)	[1]	(249)	[2]	(248)	[1]	(249)	[2]	(248)	[3]
Available-for-Sale Securities, Other Than Temporary Impairments		0	[4]	0	[5]	0	[4]	0	[5]	0	[6]
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
Available-for-sale Securities, Debt Maturities, One to Five Years, Amortized Cost Basis		0				0
Available-for-sale Securities, Debt Maturities, Six To Ten Years, Amortized Cost Basis		0				0
Available-for-sale Securities, Debt Maturities, Over Ten Years, Amortized Cost Basis		4,400				4,400
Available-for-sale Securities, Debt Maturities, Single Maturity Date, Amortized Cost Basis		4,400				4,400
Available-for-sale Securities, Debt Maturities, Amortized Cost		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
Available-for-sale Securities, Debt Maturities, One to Five Years, Fair Value		0				0
Available-for-sale Securities, Debt Maturities, Six to Ten Years, Fair Value		0				0
Available-for-sale Securities, Debt Maturities, Over Ten Years, Fair Value		4,152				4,152
Available-for-sale Securities, Debt Maturities, Single Maturity Date		4,152				4,152
Available-for-sale Securities, Debt Maturities, Fair Value		$ 4,152		$ 4,151		$ 4,152		$ 4,151		$ 4,152
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%
Available-for-sale Securities, Debt Maturities, One to Five Years, Nominal Yield		0.00%				0.00%
Available-for-sale Securities, Debt Maturities, Six To Ten Years, Nominal Yield		0.00%				0.00%
Available-for-sale Securities, Debt Maturities, Over Ten Years, Nominal Yield	[9]	1.71%				1.71%
Available-for-sale Securities, Debt Maturities, Nominal Yield		1.71%				1.71%
Available-for-sale Securities, Debt Maturities, Weighted Average Maturity	[7]	30.16				30.16
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
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
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		4,152		4,151		4,152		4,151		4,152
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		4,152		4,151		4,152		4,151		4,152
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
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		248		249		248		249		248
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		248		249		248		249		248
Residential Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost		5,468,038		5,692,596		5,468,038		5,692,596		5,576,543
Available-for-sale Securities, Fair Value		5,485,760		5,826,581		5,485,760		5,826,581		5,575,921
Available-for-sale Securities, Gross Unrealized Gain		52,418	[1]	135,880	[2]	52,418	[1]	135,880	[2]	50,377	[3]
Available-for-sale Securities, Gross Unrealized Loss		(34,696)	[1]	(1,119)	[2]	(34,696)	[1]	(1,119)	[2]	(50,781)	[3]
Available-for-Sale Securities, Other Than Temporary Impairments		0	[4]	(776)	[5]	0	[4]	(776)	[5]	(218)	[6]
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		5,468,038				5,468,038
Available-for-sale Securities, Debt Maturities, Amortized Cost		5,468,038		5,692,596		5,468,038		5,692,596		5,576,543
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Fair Value		5,485,760				5,485,760
Available-for-sale Securities, Debt Maturities, Fair Value		$ 5,485,760		$ 5,826,581		$ 5,485,760		$ 5,826,581		$ 5,575,921
Available-for-sale Securities, Debt Maturities, Nominal Yield [Abstract]
Available-for-sale Securities, Debt Maturities, Nominal Yield	[10]	1.94%				1.94%
Available-for-sale Securities, Debt Maturities, Average Expected Life of Mortgage-backed Securities						3 years 329 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		139		30		139		30		186
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		$ 2,425,303		$ 463,130		$ 2,425,303		$ 463,130		$ 3,308,229
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		180,364		53,907		180,364		53,907		129,716
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		2,605,667		517,037		2,605,667		517,037		3,437,945
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		31,310		1,156		31,310		1,156		47,767
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		3,386		739		3,386		739		3,232
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		34,696		1,895		34,696		1,895		50,999
U.S. government agency residential mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost		5,381,382		5,577,287		5,381,382		5,577,287		5,475,351
Available-for-sale Securities, Fair Value		5,382,377		5,700,268		5,382,377		5,700,268		5,460,386
Available-for-sale Securities, Gross Unrealized Gain		35,691	[1]	124,064	[2]	35,691	[1]	124,064	[2]	35,800	[3]
Available-for-sale Securities, Gross Unrealized Loss		(34,696)	[1]	(1,083)	[2]	(34,696)	[1]	(1,083)	[2]	(50,765)	[3]
Available-for-Sale Securities, Other Than Temporary Impairments		0	[4]	0	[5]	0	[4]	0	[5]	0	[6]
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Amortized Cost		5,381,382		5,577,287		5,381,382		5,577,287		5,475,351
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Fair Value		$ 5,382,377		$ 5,700,268		$ 5,382,377		$ 5,700,268		$ 5,460,386
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions		139		16		139		16		180
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		$ 2,425,303		$ 447,541		$ 2,425,303		$ 447,541		$ 3,300,298
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		180,364		37,739		180,364		37,739		116,208
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		2,605,667		485,280		2,605,667		485,280		3,416,506
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		31,310		879		31,310		879		47,593
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		3,386		204		3,386		204		3,172
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		34,696		1,083		34,696		1,083		50,765
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		3,005,920		2,908,698		3,005,920		2,908,698		3,062,525
Available-for-sale Securities, Fair Value		3,008,531		2,988,974		3,008,531		2,988,974		3,055,676
Available-for-sale Securities, Gross Unrealized Gain		24,213	[1]	80,549	[2]	24,213	[1]	80,549	[2]	25,066	[3]
Available-for-sale Securities, Gross Unrealized Loss		(21,602)	[1]	(273)	[2]	(21,602)	[1]	(273)	[2]	(31,915)	[3]
Available-for-Sale Securities, Other Than Temporary Impairments		0	[4]	0	[5]	0	[4]	0	[5]	0	[6]
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Amortized Cost		3,005,920		2,908,698		3,005,920		2,908,698		3,062,525
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Fair Value		$ 3,008,531		$ 2,988,974		$ 3,008,531		$ 2,988,974		$ 3,055,676
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions		75		4		75		4		91
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		$ 1,381,687		$ 97,910		$ 1,381,687		$ 97,910		$ 1,787,644
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		87,371		15,401		87,371		15,401		72,105
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		1,469,058		113,311		1,469,058		113,311		1,859,749
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		20,288		267		20,288		267		30,238
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		1,314		6		1,314		6		1,677
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		21,602		273		21,602		273		31,915
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		1,412,376		1,746,661		1,412,376		1,746,661		1,534,451
Available-for-sale Securities, Fair Value		1,412,472		1,785,332		1,412,472		1,785,332		1,531,116
Available-for-sale Securities, Gross Unrealized Gain		7,785	[1]	38,869	[2]	7,785	[1]	38,869	[2]	8,475	[3]
Available-for-sale Securities, Gross Unrealized Loss		(7,689)	[1]	(198)	[2]	(7,689)	[1]	(198)	[2]	(11,810)	[3]
Available-for-Sale Securities, Other Than Temporary Impairments		0	[4]	0	[5]	0	[4]	0	[5]	0	[6]
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Amortized Cost		1,412,376		1,746,661		1,412,376		1,746,661		1,534,451
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Fair Value		$ 1,412,472		$ 1,785,332		$ 1,412,472		$ 1,785,332		$ 1,531,116
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		1		42		1		58
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		$ 731,853		$ 0		$ 731,853		$ 0		$ 964,017
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		16,388		22,338		16,388		22,338		18,307
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		748,241		22,338		748,241		22,338		982,324
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		7,213		0		7,213		0		11,210
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		476		198		476		198		600
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		7,689		198		7,689		198		11,810
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		938,086		921,928		938,086		921,928		878,375
Available-for-sale Securities, Fair Value		936,365		925,962		936,365		925,962		873,594
Available-for-sale Securities, Gross Unrealized Gain		3,641	[1]	4,646	[2]	3,641	[1]	4,646	[2]	2,259	[3]
Available-for-sale Securities, Gross Unrealized Loss		(5,362)	[1]	(612)	[2]	(5,362)	[1]	(612)	[2]	(7,040)	[3]
Available-for-Sale Securities, Other Than Temporary Impairments		0	[4]	0	[5]	0	[4]	0	[5]	0	[6]
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Amortized Cost		938,086		921,928		938,086		921,928		878,375
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Fair Value		$ 936,365		$ 925,962		$ 936,365		$ 925,962		$ 873,594
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions		21		11		21		11		31
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		$ 291,806		$ 349,631		$ 291,806		$ 349,631		$ 548,637
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		76,605		0		76,605		0		25,796
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		368,411		349,631		368,411		349,631		574,433
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		3,766		612		3,766		612		6,145
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		1,596		0		1,596		0		895
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		5,362		612		5,362		612		7,040
U.S. government agency residential mortgage-backed securities | Other
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost		25,000				25,000
Available-for-sale Securities, Fair Value		25,009				25,009
Available-for-sale Securities, Gross Unrealized Gain	[1]	52				52
Available-for-sale Securities, Gross Unrealized Loss	[1]	(43)				(43)
Available-for-Sale Securities, Other Than Temporary Impairments		0				0
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Amortized Cost		25,000				25,000
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Fair Value		$ 25,009				$ 25,009
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				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		$ 19,957				$ 19,957
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		0				0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		19,957				19,957
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		43				43
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		0				0
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		43				43
Privately issued residential mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost		86,656		115,309		86,656		115,309		101,192
Available-for-sale Securities, Fair Value		103,383		126,313		103,383		126,313		115,535
Available-for-sale Securities, Gross Unrealized Gain		16,727	[1]	11,816	[2]	16,727	[1]	11,816	[2]	14,577	[3]
Available-for-sale Securities, Gross Unrealized Loss		0	[1]	(36)	[2]	0	[1]	(36)	[2]	(16)	[3]
Available-for-Sale Securities, Other Than Temporary Impairments		0	[4]	(776)	[5]	0	[4]	(776)	[5]	(218)	[6]
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Amortized Cost		86,656		115,309		86,656		115,309		101,192
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Fair Value		$ 103,383		$ 126,313		$ 103,383		$ 126,313		$ 115,535
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		14	[11]	0		14	[11]	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		$ 0		$ 15,589	[11]	$ 0		$ 15,589	[11]	$ 7,931	[12]
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		0		16,168	[11]	0		16,168	[11]	13,508	[12]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		0		31,757	[11]	0		31,757	[11]	21,439	[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		0		277	[11]	0		277	[11]	174	[12]
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		0		535	[11]	0		535	[11]	60	[12]
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		0		812	[11]	0		812	[11]	234	[12]
Privately issued residential mortgage-backed securities | Alt A loans Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost		38,334		49,522		38,334		49,522		44,245
Available-for-sale Securities, Fair Value		46,903		54,536		46,903		54,536		51,512
Available-for-sale Securities, Gross Unrealized Gain		8,569	[1]	5,461	[2]	8,569	[1]	5,461	[2]	7,485	[3]
Available-for-sale Securities, Gross Unrealized Loss		0	[1]	0	[2]	0	[1]	0	[2]	0	[3]
Available-for-Sale Securities, Other Than Temporary Impairments		0	[4]	(447)	[5]	0	[4]	(447)	[5]	(218)	[6]
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Amortized Cost		38,334		49,522		38,334		49,522		44,245
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Fair Value		$ 46,903		$ 54,536		$ 46,903		$ 54,536		$ 51,512
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		5	[11]	0		5	[11]	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		$ 0		$ 8,513	[11]	$ 0		$ 8,513	[11]	$ 7,931	[12]
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		0		8,291	[11]	0		8,291	[11]	7,410	[12]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		0		16,804	[11]	0		16,804	[11]	15,341	[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		0		241	[11]	0		241	[11]	174	[12]
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		0		206	[11]	0		206	[11]	44	[12]
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		0		447	[11]	0		447	[11]	218	[12]
Privately issued residential mortgage-backed securities | Jumbo A loans [Member]
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost		48,322		65,787		48,322		65,787		56,947
Available-for-sale Securities, Fair Value		56,480		71,777		56,480		71,777		64,023
Available-for-sale Securities, Gross Unrealized Gain		8,158	[1]	6,355	[2]	8,158	[1]	6,355	[2]	7,092	[3]
Available-for-sale Securities, Gross Unrealized Loss		0	[1]	(36)	[2]	0	[1]	(36)	[2]	(16)	[3]
Available-for-Sale Securities, Other Than Temporary Impairments		0	[4]	(329)	[5]	0	[4]	(329)	[5]	0	[6]
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Amortized Cost		48,322		65,787		48,322		65,787		56,947
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Fair Value		$ 56,480		$ 71,777		$ 56,480		$ 71,777		$ 64,023
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		9	[11]	0		9	[11]	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		$ 0		$ 7,076	[11]	$ 0		$ 7,076	[11]	$ 0	[12]
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		0		7,877	[11]	0		7,877	[11]	6,098	[12]
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		0		14,953	[11]	0		14,953	[11]	6,098	[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		0		36	[11]	0		36	[11]	0	[12]
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		0		329	[11]	0		329	[11]	16	[12]
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		0		365	[11]	0		365	[11]	16	[12]
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		30,134				30,134
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, without Single Maturity Date, Fair Value		$ 35,296				$ 35,296
Available-for-sale Securities, Debt Maturities, Nominal Yield [Abstract]
Available-for-sale Securities, Debt Maturities, Nominal Yield		0.00%				0.00%
Perpetual preferred stock
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost		$ 12,562		15,562		$ 12,562		15,562		15,561
Available-for-sale Securities, Fair Value		16,568		17,931		16,568		17,931		18,474
Available-for-sale Securities, Gross Unrealized Gain		4,006	[1]	2,369	[2]	4,006	[1]	2,369	[2]	2,913	[3]
Available-for-sale Securities, Gross Unrealized Loss		0	[1]	0	[2]	0	[1]	0	[2]	0	[3]
Available-for-Sale Securities, Other Than Temporary Impairments		0	[4]	0	[5]	0	[4]	0	[5]	0	[6]
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Amortized Cost		12,562		15,562		12,562		15,562		15,561
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Fair Value		$ 16,568		$ 17,931		$ 16,568		$ 17,931		$ 18,474
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
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
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		0		0		0		0		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		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
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		0		0		0		0		0
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		0		0		0		0		0
Equity securities and mutual funds
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Amortized Cost		17,572		17,270		17,572		17,270		17,424
Available-for-sale Securities, Fair Value		18,728		18,814		18,728		18,814		18,357
Available-for-sale Securities, Gross Unrealized Gain		1,219	[1]	1,558	[2]	1,219	[1]	1,558	[2]	1,060	[3]
Available-for-sale Securities, Gross Unrealized Loss		(63)	[1]	(14)	[2]	(63)	[1]	(14)	[2]	(127)	[3]
Available-for-Sale Securities, Other Than Temporary Impairments		0	[4]	0	[5]	0	[4]	0	[5]	0	[6]
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Amortized Cost		17,572		17,270		17,572		17,270		17,424
Available-for-sale Securities, Debt Maturities, Fair Value, Rolling Maturity [Abstract]
Available-for-sale Securities, Debt Maturities, Fair Value		$ 18,728		$ 18,814		$ 18,728		$ 18,814		$ 18,357
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Available-for-sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions		91		30		91		30		104
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		$ 1,668		$ 0		$ 1,668		$ 0		$ 2,127
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value		887		889		887		889		817
Available-for-sale Securities, Continuous Unrealized Loss Position, Fair Value		2,555		889		2,555		889		2,944
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		22		0		22		0		41
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss		41		14		41		14		86
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss		$ 63		$ 14		$ 63		$ 14		$ 127

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

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