Investment Securities (Tables)

12 Months Ended

Dec. 31, 2017

Investments, Debt and Equity Securities [Abstract]

Investment securities, at fair value, consisted of the following at December 31, 2017 and 2016.



(In thousands)	2017		2016
Available for sale:
U.S. government and federal agency obligations	$	917,147	$	920,904
Government-sponsored enterprise obligations	406,363		449,998
State and municipal obligations	1,611,366		1,778,214
Agency mortgage-backed securities	3,040,913		2,685,931
Non-agency mortgage-backed securities	905,793		1,055,639
Asset-backed securities	1,492,800		2,381,301
Other debt securities	351,060		325,953
Equity securities	48,838		51,263
Total available for sale	8,774,280		9,649,203
Trading	18,269		22,225
Non-marketable	100,758		99,558
Total investment securities	$	8,893,307	$	9,770,986

Summary Of Available For Sale Investment Securities By Maturity Groupings



(Dollars in thousands)	Amortized Cost		Fair Value		Weighted Average Yield
U.S. government and federal agency obligations:
Within 1 year	$	57,983	$	58,347	1.71
After 1 but within 5 years	641,114		639,192		1.45
After 5 but within 10 years	149,589		149,927		.43
After 10 years	68,808		69,681		.59
Total U.S. government and federal agency obligations	917,494		917,147		1.24
Government-sponsored enterprise obligations:
Within 1 year	215,763		215,434		1.35
After 1 but within 5 years	121,575		121,199		1.93
After 5 but within 10 years	34,983		34,870		2.71
After 10 years	35,945		34,860		3.00
Total government-sponsored enterprise obligations	408,266		406,363		1.79
State and municipal obligations:
Within 1 year	164,756		165,638		2.65
After 1 but within 5 years	665,351		670,953		2.21
After 5 but within 10 years	709,248		721,181		2.46
After 10 years	53,352		53,594		3.01
Total state and municipal obligations	1,592,707		1,611,366		2.39
Mortgage and asset-backed securities:
Agency mortgage-backed securities	3,046,701		3,040,913		2.62
Non-agency mortgage-backed securities	903,920		905,793		2.54
Asset-backed securities	1,495,380		1,492,800		2.03
Total mortgage and asset-backed securities	5,446,001		5,439,506		2.45
Other debt securities:
Within 1 year	10,390		10,389
After 1 but within 5 years	247,181		247,626
After 5 but within 10 years	93,417		93,045
Total other debt securities	350,988		351,060
Equity securities	4,411		48,838
Total available for sale investment securities	$	8,719,867	$	8,774,280

Available For Sale Securities Unrealized Gains And Losses By Security Type

For securities classified as available for sale, the following table shows the unrealized gains and losses (pre-tax) in accumulated other comprehensive income, by security type.



(In thousands)	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
December 31, 2017
U.S. government and federal agency obligations	$	917,494	$	4,096	$	(4,443	)	$	917,147
Government-sponsored enterprise obligations	408,266		26		(1,929		)	406,363
State and municipal obligations	1,592,707		21,413		(2,754		)	1,611,366
Mortgage and asset-backed securities:
Agency mortgage-backed securities	3,046,701		17,956		(23,744		)	3,040,913
Non-agency mortgage-backed securities	903,920		6,710		(4,837		)	905,793
Asset-backed securities	1,495,380		2,657		(5,237		)	1,492,800
Total mortgage and asset-backed securities	5,446,001		27,323		(33,818		)	5,439,506
Other debt securities	350,988		1,250		(1,178		)	351,060
Equity securities	4,411		44,427		—			48,838
Total	$	8,719,867	$	98,535	$	(44,122	)	$	8,774,280
December 31, 2016
U.S. government and federal agency obligations	$	919,904	$	7,312	$	(6,312	)	$	920,904
Government-sponsored enterprise obligations	450,448		1,126		(1,576		)	449,998
State and municipal obligations	1,778,684		12,223		(12,693		)	1,778,214
Mortgage and asset-backed securities:
Agency mortgage-backed securities	2,674,964		31,610		(20,643		)	2,685,931
Non-agency mortgage-backed securities	1,054,446		7,686		(6,493		)	1,055,639
Asset-backed securities	2,389,176		3,338		(11,213		)	2,381,301
Total mortgage and asset-backed securities	6,118,586		42,634		(38,349		)	6,122,871
Other debt securities	327,030		935		(2,012		)	325,953
Equity securities	5,678		45,585		—			51,263
Total	$	9,600,330	$	109,815	$	(60,942	)	$	9,649,203

Cash Flow Model Inputs Used To Calculate Credit Losses

The credit-related portion of the loss on these securities was based on the cash flows projected to be received over the estimated life of the securities, discounted to present value, and compared to the current amortized cost bases of the securities. Significant inputs to the cash flow models used to calculate the credit losses on these securities included the following:



Significant Inputs	Range
Prepayment CPR	0%	-	25%
Projected cumulative default	14%	-	50%
Credit support	0%	-	54%
Loss severity	15%	-	63%

Changes In Recorded Credit Losses

The following table presents a rollforward of the cumulative OTTI credit losses recognized in earnings on all available for sale debt securities.



(In thousands)	2017			2016			2015
Cumulative OTTI credit losses at January 1	$	14,080		$	14,129		$	13,734
Credit losses on debt securities for which impairment was not previously recognized	111			—			76
Credit losses on debt securities for which impairment was previously recognized	274			270			407
Increase in expected cash flows that are recognized over remaining life of security	(266		)	(319		)	(88		)
Cumulative OTTI credit losses at December 31	$	14,199		$	14,080		$	14,129

Securities With Unrealized Losses And Length Of Impairment Period

Securities with unrealized losses recorded in accumulated other comprehensive income are shown in the table below, along with the length of the impairment period.



	Less than 12 months				12 months or longer				Total
(In thousands)	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
December 31, 2017
U.S. government and federal agency obligations	$	618,617	$	4,443	$	—	$	—	$	618,617	$	4,443
Government-sponsored enterprise obligations	286,393		1,712		49,766		217		336,159		1,929
State and municipal obligations	282,843		1,752		49,339		1,002		332,182		2,754
Mortgage and asset-backed securities:
Agency mortgage-backed securities	1,320,689		9,433		619,300		14,311		1,939,989		23,744
Non-agency mortgage-backed securities	577,017		2,966		153,813		1,871		730,830		4,837
Asset-backed securities	786,048		3,168		264,295		2,069		1,050,343		5,237
Total mortgage and asset-backed securities	2,683,754		15,567		1,037,408		18,251		3,721,162		33,818
Other debt securities	144,090		727		20,202		451		164,292		1,178
Total	$	4,015,697	$	24,201	$	1,156,715	$	19,921	$	5,172,412	$	44,122
December 31, 2016
U.S. government and federal agency obligations	$	349,538	$	2,823	$	32,208	$	3,489	$	381,746	$	6,312
Government-sponsored enterprise obligations	190,441		1,576		—		—		190,441		1,576
State and municipal obligations	700,779		12,164		15,195		529		715,974		12,693
Mortgage and asset-backed securities:
Agency mortgage-backed securities	1,147,416		20,638		2,150		5		1,149,566		20,643
Non-agency mortgage-backed securities	688,131		6,373		34,946		120		723,077		6,493
Asset-backed securities	780,209		5,277		358,778		5,936		1,138,987		11,213
Total mortgage and asset-backed securities	2,615,756		32,288		395,874		6,061		3,011,630		38,349
Other debt securities	179,639		1,986		975		26		180,614		2,012
Total	$	4,036,153	$	50,837	$	444,252	$	10,105	$	4,480,405	$	60,942

State And Municipal Obligations, By State And Economic Sector

The Company’s holdings of state and municipal obligations included gross unrealized losses of $2.8 million at December 31, 2017. The state and municipal portfolio totaled $1.6 billion at fair value, or 18.4% of total available for sale securities. The portfolio is diversified in order to reduce risk, and the Company has processes and procedures in place to monitor its state and municipal holdings, identify signs of financial distress and, if necessary, exit its positions in a timely manner.

Credit Ratings In State And Municipal Bond Portfolio

The credit ratings (Moody’s rating or equivalent) at December 31, 2017 in the state and municipal bond portfolio are shown in the following table. The average credit quality of the portfolio is Aa2 as rated by Moody’s.



	% of Portfolio
Aaa	6.0	%
Aa	76.9
A	16.4
Not rated	.7
	100.0	%

Proceeds From Sales Of Securities And Components Of Investment Securities Gains And Losses

The following table presents proceeds from sales of securities and the components of investment securities gains and losses which have been recognized in earnings.



(In thousands)	2017			2016			2015
Proceeds from sales of available for sale securities	$	790,152		$	2,049		$	675,870
Proceeds from sales of non-marketable securities	2,228			22,331			13,161
Total proceeds	$	792,380		$	24,380		$	689,031
Available for sale:
Gains realized on sales	$	10,656		$	109		$	2,925
Losses realized on sales	(10,297		)	—			—
Losses realized on called bonds	(254		)	—			—
Gain realized on donation	31,074			—			—
Other-than-temporary impairment recognized on debt securities	(385		)	(270		)	(483		)
Non-marketable:
Gains realized on sales	970			4,349			2,516
Losses realized on sales	(880		)	(502		)	(40		)
Fair value adjustments, net	(5,833		)	(3,739		)	1,402
Investment securities gains (losses), net	$	25,051		$	(53	)	$	6,320