Investment Securities (Tables)

6 Months Ended

Jun. 30, 2018

Investments, Debt and Equity Securities [Abstract]

Amortized Cost and Fair Value of Available-for-Sale and Held-to-Maturity Investment Securities Portfolio

The following table summarizes the amortized cost and fair value of the available-for-sale and held-to-maturity investment securities portfolio at June 30, 2018 and December 31, 2017 and the corresponding amounts of unrealized gains and losses therein:

(dollars in thousands)	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
June 30, 2018
Available-for-Sale
U.S. Treasury	$	5,312	$	—	$	(55	)	$	5,257
U.S. government-sponsored entities and agencies		583,644		—		(15,413	)		568,231
Mortgage-backed securities - Agency		1,503,636		501		(55,611	)		1,448,526
States and political subdivisions		793,141		8,406		(4,014	)		797,533
Pooled trust preferred securities		13,887		—		(5,682	)		8,205
Other securities		359,820		345		(6,252	)		353,913
Total available-for-sale securities	$	3,259,440	$	9,252	$	(87,027	)	$	3,181,665
Held-to-Maturity
U.S. government-sponsored entities and agencies	$	73,570	$	—	$	(2,286	)	$	71,284
Mortgage-backed securities - Agency		139,594		58		(3,868	)		135,784
States and political subdivisions		312,554		7,209		(2,234	)		317,529
Total held-to-maturity securities	$	525,718	$	7,267	$	(8,388	)	$	524,597
December 31, 2017
Available-for-Sale
U.S. Treasury	$	5,473	$	83	$	(5	)	$	5,551
U.S. government-sponsored entities and agencies		675,643		3		(11,360	)		664,286
Mortgage-backed securities - Agency		1,704,014		1,600		(37,932	)		1,667,682
States and political subdivisions		529,835		5,085		(4,727	)		530,193
Pooled trust preferred securities		16,605		—		(8,157	)		8,448
Other securities		321,016		1,172		(2,141	)		320,047
Total available-for-sale securities	$	3,252,586	$	7,943	$	(64,322	)	$	3,196,207
Held-to-Maturity
Mortgage-backed securities - Agency	$	6,903	$	153	$	—		$	7,056
States and political subdivisions		677,160		43,495		(8	)		720,647
Total held-to-maturity securities	$	684,063	$	43,648	$	(8	)	$	727,703

Schedule of Proceeds from Sales or Calls and Realized Gain and Losses of Available-for-Sale Investment Securities and Other Securities

Proceeds from sales or calls of available-for-sale investment securities, the resulting realized gains and realized losses, and other securities gains or losses were as follows for the three and six months ended June 30, 2018 and 2017:

	Three Months Ended June 30,						Six Months Ended June 30,
(dollars in thousands)	2018			2017			2018			2017
Proceeds from sales of available-for-sale securities	$	47,064		$	152,689		$	131,321		$	186,277
Proceeds from calls of available-for-sale securities		11,211			60,600			28,647			71,120
Total	$	58,275		$	213,289		$	159,968		$	257,397
Realized gains on sales of available-for-sale securities	$	1,251		$	2,954		$	3,259		$	4,283
Realized gains on calls of available-for-sale securities		283			—			284			—
Realized losses on sales of available-for-sale securities		(48	)		(13	)		(1,305	)		(43	)
Realized losses on calls of available-for-sale securities		(4	)		(7	)		(53	)		(8	)
Other securities gains (losses) (1)		12			141			97			343
Net securities gains (losses)	$	1,494		$	3,075		$	2,282		$	4,575

(1) Other securities gains (losses) includes net realized and unrealized gains or losses associated with trading securities and mutual funds.

Expected Maturities of Investment Securities Portfolio

 Weighted average yield is based on amortized cost.

	At June 30, 2018
(dollars in thousands)					Weighted
	Amortized		Fair		Average
Maturity	Cost		Value		Yield
Available-for-Sale
Within one year	$	60,410	$	60,376		2.22	%
One to five years		511,930		505,586		2.29
Five to ten years		383,847		380,192		3.03
Beyond ten years		2,303,253		2,235,511		2.64
Total	$	3,259,440	$	3,181,665		2.62	%
Held-to-Maturity
Within one year	$	27,128	$	27,341		3.75	%
One to five years		33,736		34,432		4.06
Five to ten years		75,966		77,962		4.38
Beyond ten years		388,888		384,862		3.59
Total	$	525,718	$	524,597		3.74	%

Available-for-Sale and Held-to-Maturity Investment Securities with Unrealized Losses by Aggregated Major Security Type and Length of Time in Continuous Unrealized Loss Position

The following table summarizes the available-for-sale investment securities with unrealized losses at June 30, 2018 and December 31, 2017 by aggregated major security type and length of time in a continuous unrealized loss position:

	Less than 12 months					12 months or longer					Total
(dollars in thousands)	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
June 30, 2018
Available-for-Sale
U.S. Treasury	$	5,257	$	(55	)	$	—	$	—		$	5,257	$	(55	)
U.S. government-sponsored entities and agencies		178,133		(3,476	)		390,097		(11,937	)		568,230		(15,413	)
Mortgage-backed securities - Agency		728,486		(20,942	)		657,333		(34,669	)		1,385,819		(55,611	)
States and political subdivisions		278,063		(3,761	)		8,239		(253	)		286,302		(4,014	)
Pooled trust preferred securities		—		—			8,205		(5,682	)		8,205		(5,682	)
Other securities		186,479		(3,599	)		110,953		(2,653	)		297,432		(6,252	)
Total available-for-sale	$	1,376,418	$	(31,833	)	$	1,174,827	$	(55,194	)	$	2,551,245	$	(87,027	)
December 31, 2017
Available-for-Sale
U.S. Treasury	$	1,480	$	(5	)	$	—	$	—		$	1,480	$	(5	)
U.S. government-sponsored entities and agencies		201,773		(1,333	)		408,493		(10,027	)		610,266		(11,360	)
Mortgage-backed securities - Agency		789,804		(8,692	)		774,825		(29,240	)		1,564,629		(37,932	)
States and political subdivisions		196,024		(1,899	)		90,637		(2,828	)		286,661		(4,727	)
Pooled trust preferred securities		—		—			8,448		(8,157	)		8,448		(8,157	)
Other securities		61,260		(429	)		125,517		(1,712	)		186,777		(2,141	)
Total available-for-sale	$	1,250,341	$	(12,358	)	$	1,407,920	$	(51,964	)	$	2,658,261	$	(64,322	)

The following table summarizes the held-to-maturity investment securities with unrecognized losses at June 30, 2018 and December 31, 2017 by aggregated major security type and length of time in a continuous unrecognized loss position:

	Less than 12 months					12 months or longer					Total
(dollars in thousands)	Fair Value		Unrecognized Losses			Fair Value		Unrecognized Losses			Fair Value		Unrecognized Losses
June 30, 2018
Held-to-Maturity
U.S. government-sponsored entities and agencies	$	—	$	—		$	71,284	$	(5,716	)	$	71,284	$	(5,716	)
Mortgage-backed securities - Agency		35,489		(992	)		99,239		(9,029	)		134,728		(10,021	)
States and political subdivisions		36,231		(1,466	)		70,130		(3,692	)		106,361		(5,158	)
Total held-to-maturity	$	71,720	$	(2,458	)	$	240,653	$	(18,437	)	$	312,373	$	(20,895	)
December 31, 2017
Held-to-Maturity
States and political subdivisions	$	2,309	$	(8	)	$	—	$	—		$	2,309	$	(8	)
Total held-to-maturity	$	2,309	$	(8	)	$	—	$	—		$	2,309	$	(8	)

Trust Preferred Securities

The table below summarizes the relevant characteristics of our pooled trust preferred securities as well as our single issuer trust preferred securities that are included in the “other securities” category in this footnote. Each of the pooled trust preferred securities support a more senior tranche of security holders. Both pooled trust preferred securities have experienced credit defaults. However, these securities have excess subordination and are not other-than-temporarily impaired as a result of their class hierarchy, which provides more loss protection.

Trust preferred securities June 30, 2018 (dollars in thousands)	Class		Lowest Credit Rating (1)		Amortized Cost		Fair Value		Unrealized Gain/ (Loss)			Realized Losses 2018		# of Issuers Currently Performing/ Remaining		Actual Deferrals and Defaults as a % of Original Collateral			Expected Defaults as a % of Remaining Performing Collateral			Excess Subordination as a % of Current Performing Collateral
Pooled trust preferred securities:
Pretsl XXVII LTD		B		B	$	4,382	$	2,602	$	(1,780	)	$	—		35/44		16.7	%		4.2	%		46.1	%
Trapeza Ser 13A		A2A		BBB		9,505		5,603		(3,902	)		—		48/53		4.5	%		4.7	%		45.5	%
						13,887		8,205		(5,682	)		—
Single Issuer trust preferred securities:
JP Morgan Chase Cap XIII				BBB-		4,783		4,550		(233	)		—
Total					$	18,670	$	12,755	$	(5,915	)	$	—

(1) Lowest rating for the security provided by any nationally recognized credit rating agency.