Investment Securities (Tables)

6 Months Ended

Jun. 30, 2017

Investment Securities

Schedule of amortized cost and fair value of securities

	June 30, 2017								December 31, 2016
	Amortized		Unrealized		Unrealized		Fair		Amortized		Unrealized		Unrealized		Fair
(dollars in thousands)	Cost		Gains		Losses		Value		Cost		Gains		Losses		Value
U.S. Treasury securities	$	405,011	$	—	$	(8,169)	$	396,842	$	405,637	$	—	$	(13,164)	$	392,473
Government-sponsored enterprises debt securities		249,709		54		(4,445)		245,318		249,707		16		(7,056)		242,667
Government agency mortgage-backed securities		173,078		—		(4,280)		168,798		190,485		—		(4,822)		185,663
Government-sponsored enterprises mortgage-backed securities		194,340		267		(2,990)		191,617		208,034		385		(4,034)		204,385
Non-government asset-backed securities		3,802		—		(1)		3,801		12,592		—		(9)		12,583
Collateralized mortgage obligations:
Government agency		3,345,644		1,760		(38,085)		3,309,319		3,409,822		794		(58,794)		3,351,822
Government-sponsored enterprises		821,593		1,236		(11,655)		811,174		700,338		789		(13,206)		687,921
Total available-for-sale securities	$	5,193,177	$	3,317	$	(69,625)	$	5,126,869	$	5,176,615	$	1,984	$	(101,085)	$	5,077,514

Schedule of amortized cost and fair value of debt securities by contractual maturity

	June 30, 2017
	Amortized		Fair
(dollars in thousands)	Cost		Value
Due after one year through five years	$	305,580	$	299,129
Due after five years through ten years		349,140		343,031
		654,720		642,160
Government agency mortgage-backed securities		173,078		168,798
Government-sponsored enterprises mortgage-backed securities		194,340		191,617
Non-government asset-backed securities		3,802		3,801
Collateralized mortgage obligations:
Government agency		3,345,644		3,309,319
Government-sponsored enterprises		821,593		811,174
Total mortgage- and asset-backed securities		4,538,457		4,484,709
Total available-for-sale securities	$	5,193,177	$	5,126,869

Schedule of unrealized gross losses and fair values of securities in a continuous loss position

	Time in Continuous Loss as of June 30, 2017
	Less Than 12 Months				12 Months or More				Total
	Unrealized				Unrealized				Unrealized
(dollars in thousands)	Losses		Fair Value		Losses		Fair Value		Losses		Fair Value
U.S. Treasury securities	$	(8,169)	$	396,842	$	—	$	—	$	(8,169)	$	396,842
Government-sponsored enterprises debt securities		(4,445)		210,264		—		—		(4,445)		210,264
Government agency mortgage-backed securities		(4,280)		168,798		—		—		(4,280)		168,798
Government-sponsored enterprises mortgage-backed securities		(2,990)		184,143		—		—		(2,990)		184,143
Non-government asset-backed securities		(1)		1,640		—		2,161		(1)		3,801
Collateralized mortgage obligations:
Government agency		(29,692)		2,488,757		(8,393)		329,429		(38,085)		2,818,186
Government-sponsored enterprises		(2,213)		373,103		(9,442)		254,440		(11,655)		627,543
Total available-for-sale securities with unrealized losses	$	(51,790)	$	3,823,547	$	(17,835)	$	586,030	$	(69,625)	$	4,409,577

	Time in Continuous Loss as of December 31, 2016
	Less Than 12 Months				12 Months or More				Total
	Unrealized				Unrealized				Unrealized
(dollars in thousands)	Losses		Fair Value		Losses		Fair Value		Losses		Fair Value
U.S. Treasury securities	$	(13,164)	$	392,473	$	—	$	—	$	(13,164)	$	392,473
Government-sponsored enterprises debt securities		(7,056)		207,651		—		—		(7,056)		207,651
Government agency mortgage-backed securities		(4,822)		185,663		—		—		(4,822)		185,663
Government-sponsored enterprises mortgage-backed securities		(4,034)		195,848		—		—		(4,034)		195,848
Non-government asset-backed securities		(3)		5,202		(6)		7,381		(9)		12,583
Collateralized mortgage obligations:
Government agency		(51,484)		2,847,103		(7,310)		233,706		(58,794)		3,080,809
Government-sponsored enterprises		(1,807)		252,065		(11,399)		279,282		(13,206)		531,347
Total available-for-sale securities with unrealized losses	$	(82,370)	$	4,086,005	$	(18,715)	$	520,369	$	(101,085)	$	4,606,374