Investment Securities (Tables)

3 Months Ended

Mar. 31, 2017

Investment Securities

Schedule of amortized cost and fair value of securities

	March 31, 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	$	405,326	$	—	$	(11,515)	$	393,811	$	405,637	$	—	$	(13,164)	$	392,473
Government-sponsored enterprises debt securities		249,708		32		(6,473)		243,267		249,707		16		(7,056)		242,667
Government agency mortgage-backed securities		180,756		—		(5,220)		175,536		190,485		—		(4,822)		185,663
Government-sponsored enterprises mortgage-backed securities		199,823		323		(3,831)		196,315		208,034		385		(4,034)		204,385
Non-government asset-backed securities		8,039		—		(5)		8,034		12,592		—		(9)		12,583
Collateralized mortgage obligations:
Government agency		3,451,042		615		(58,401)		3,393,256		3,409,822		794		(58,794)		3,351,822
Government-sponsored enterprises		863,091		854		(13,902)		850,043		700,338		789		(13,206)		687,921
Total available-for-sale securities	$	5,357,785	$	1,824	$	(99,347)	$	5,260,262	$	5,176,615	$	1,984	$	(101,085)	$	5,077,514

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

	March 31, 2017
	Amortized		Fair
(dollars in thousands)	Cost		Value
Due after one year through five years	$	279,806	$	272,245
Due after five years through ten years		375,228		364,833
		655,034		637,078
Government agency mortgage-backed securities		180,756		175,536
Government-sponsored enterprises mortgage-backed securities		199,823		196,315
Non-government asset-backed securities		8,039		8,034
Collateralized mortgage obligations:
Government agency		3,451,042		3,393,256
Government-sponsored enterprises		863,091		850,043
Total mortgage- and asset-backed securities		4,702,751		4,623,184
Total available-for-sale securities	$	5,357,785	$	5,260,262

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

	Time in Continuous Loss as of March 31, 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	$	(11,515)	$	393,811	$	—	$	—	$	(11,515)	$	393,811
Government-sponsored enterprises debt securities		(6,473)		208,235		—		—		(6,473)		208,235
Government agency mortgage-backed securities		(5,220)		175,536		—		—		(5,220)		175,536
Government-sponsored enterprises mortgage-backed securities		(3,831)		188,351		—		—		(3,831)		188,351
Non-government asset-backed securities		(2)		3,341		(3)		4,693		(5)		8,034
Collateralized mortgage obligations:
Government agency		(50,147)		2,920,271		(8,254)		246,336		(58,401)		3,166,607
Government-sponsored enterprises		(2,745)		435,537		(11,157)		266,425		(13,902)		701,962
Total available-for-sale securities with unrealized losses	$	(79,933)	$	4,325,082	$	(19,414)	$	517,454	$	(99,347)	$	4,842,536

	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