Investment Securities (Tables)

6 Months Ended

Jun. 30, 2019

Investments, Debt and Equity Securities [Abstract]

Carrying Amounts and Fair Values of Investment Securities

The carrying amounts and fair values of investment securities at June 30, 2019 and December 31, 2018 are summarized as follows:

	June 30, 2019
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized (Losses)			Fair Value
	(in thousands)
Held-to-maturity debt securities
Tax-exempt	$	435,997	$	30,861	$	—		$	466,858
Available-for-sale debt securities
CDO	$	50	$	14,976	$	—		$	15,026
Commercial MBS issued by GSEs	102,444		758		(2,361		)	100,841
Corporate debt securities	105,022		123		(6,817		)	98,328
Municipal securities	7,488		265		—			7,753
Private label residential MBS	949,699		5,605		(5,542		)	949,762
Residential MBS issued by GSEs	1,446,679		10,381		(3,744		)	1,453,316
Tax-exempt	541,879		20,023		(172		)	561,730
Trust preferred securities	32,000		—		(7,061		)	24,939
U.S. government sponsored agency securities	40,000		—		(95		)	39,905
U.S. treasury securities	1,495		2		(3		)	1,494
Total AFS debt securities	$	3,226,756	$	52,133	$	(25,795	)	$	3,253,094
Equity securities
CRA investments	$	52,516	$	—	$	(375	)	$	52,141
Preferred stock	60,871		1,964		(287		)	62,548
Total equity securities	$	113,387	$	1,964	$	(662	)	$	114,689

	December 31, 2018
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized (Losses)			Fair Value
	(in thousands)
Held-to-maturity debt securities
Tax-exempt	$	302,905	$	3,163	$	(7,420	)	$	298,648
Available-for-sale debt securities
CDO	$	50	$	15,277	$	—		$	15,327
Commercial MBS issued by GSEs	106,385		82		(6,361		)	100,106
Corporate debt securities	105,029		—		(5,649		)	99,380
Private label residential MBS	948,161		945		(24,512		)	924,594
Residential MBS issued by GSEs	1,564,181		1,415		(35,472		)	1,530,124
Tax-exempt	542,086		4,335		(7,753		)	538,668
Trust preferred securities	32,000		—		(3,383		)	28,617
U.S. government sponsored agency securities	40,000		—		(1,812		)	38,188
U.S. treasury securities	1,996		—		(12		)	1,984
Total AFS debt securities	$	3,339,888	$	22,054	$	(84,954	)	$	3,276,988
Equity securities
CRA investments	$	52,210	$	—	$	(1,068	)	$	51,142
Preferred stock	65,954		148		(2,183		)	63,919
Total equity securities	$	118,164	$	148	$	(3,251	)	$	115,061

Unrealized Losses and Fair Value of Investment Securities in Continuous Unrealized Loss Position

Information pertaining to securities with gross unrealized losses at June 30, 2019 and December 31, 2018, aggregated by investment category and length of time that individual securities have been in a continuous loss position follows: 

	June 30, 2019
	Less Than Twelve Months				More Than Twelve Months				Total
	Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value
	(in thousands)
Available-for-sale debt securities
Commercial MBS issued by GSEs	$	—	$	—	$	2,361	$	79,102	$	2,361	$	79,102
Corporate debt securities	—		—		6,817		93,183		6,817		93,183
Private label residential MBS	—		12,818		5,542		469,802		5,542		482,620
Residential MBS issued by GSEs	57		17,116		3,687		446,947		3,744		464,063
Tax-exempt	172		37,111		—		—		172		37,111
Trust preferred securities	—		—		7,061		24,939		7,061		24,939
U.S. government sponsored agency securities	—		—		95		34,905		95		34,905
U.S. treasury securities	—		—		3		995		3		995
Total AFS securities	$	229	$	67,045	$	25,566	$	1,149,873	$	25,795	$	1,216,918

	December 31, 2018
	Less Than Twelve Months				More Than Twelve Months				Total
	Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value
	(in thousands)
Held-to-maturity debt securities
Tax-exempt	$	3,868	$	91,095	$	3,552	$	69,991	$	7,420	$	161,086
Available-for-sale debt securities
Commercial MBS issued by GSEs	$	—	$	—	$	6,361	$	98,275	$	6,361	$	98,275
Corporate debt securities	16		5,013		5,633		94,367		5,649		99,380
Private label residential MBS	5,173		217,982		19,339		537,316		24,512		755,298
Residential MBS issued by GSEs	1,363		141,493		34,109		1,215,490		35,472		1,356,983
Tax-exempt	3,562		209,767		4,191		72,382		7,753		282,149
Trust preferred securities	—		—		3,383		28,617		3,383		28,617
U.S. government sponsored agency securities	—		—		1,812		38,188		1,812		38,188
U.S. treasury securities	—		—		12		1,984		12		1,984
Total AFS securities	$	10,114	$	574,255	$	74,840	$	2,086,619	$	84,954	$	2,660,874

Amortized Cost and Fair Value of Investment Securities by Contractual Maturities

The amortized cost and fair value of securities as of June 30, 2019, by contractual maturities, are shown below. MBS are shown separately as individual MBS are comprised of pools of loans with varying maturities. Therefore, these securities are listed separately in the maturity summary. 

	June 30, 2019
	Amortized Cost		Estimated Fair Value
	(in thousands)
Held-to-maturity
Due in one year or less	$	10,100	$	10,139
After one year through five years	24,940		25,714
After ten years	400,957		431,005
Total HTM securities	$	435,997	$	466,858
Available-for-sale
Due in one year or less	$	3,781	$	3,789
After one year through five years	16,012		16,173
After five years through ten years	209,275		203,657
After ten years	498,866		525,556
Mortgage-backed securities	2,498,822		2,503,919
Total AFS securities	$	3,226,756	$	3,253,094

Investment Securities by Credit Rating Type

The following tables summarize the carrying amount of the Company’s investment ratings position as of June 30, 2019 and December 31, 2018: 

	June 30, 2019
	AAA		Split-rated AAA/AA+		AA+ to AA-		A+ to A-		BBB+ to BBB-		BB+ and below		Unrated		Totals
	(in thousands)
Held-to-maturity debt securities
Tax-exempt	$	—	$	—	$	—	$	—	$	—	$	—	$	435,997	$	435,997
Available-for-sale debt securities
CDO	$	—	$	—	$	—	$	—	$	—	$	15,026	$	—	$	15,026
Commercial MBS issued by GSEs	—		100,841		—		—		—		—		—		100,841
Corporate debt securities	—		—		—		65,244		33,084		—		—		98,328
Municipal securities	—		—		—		—		—		—		7,753		7,753
Private label residential MBS	926,847		—		20,454		256		881		1,324		—		949,762
Residential MBS issued by GSEs	—		1,453,316		—		—		—		—		—		1,453,316
Tax-exempt	69,310		8,922		309,263		174,235		—		—		—		561,730
Trust preferred securities	—		—		—		—		24,939		—		—		24,939
U.S. government sponsored agency securities	—		39,905		—		—		—		—		—		39,905
U.S. treasury securities	—		1,494		—		—		—		—		—		1,494
Total AFS securities	$	996,157	$	1,604,478	$	329,717	$	239,735	$	58,904	$	16,350	$	7,753	$	3,253,094
Equity securities
CRA investments	$	—	$	25,375	$	—	$	—	$	—	$	—	$	26,766	$	52,141
Preferred stock	—		—		—		—		48,975		4,030		9,543		62,548
Total equity securities	$	—	$	25,375	$	—	$	—	$	48,975	$	4,030	$	36,309	$	114,689

(1)Where ratings differ, the Company uses an average of the available ratings by major credit agencies.

	December 31, 2018
	AAA		Split-rated AAA/AA+		AA+ to AA-		A+ to A-		BBB+ to BBB-		BB+ and below		Unrated		Totals
	(in thousands)
Held-to-maturity debt securities
Tax-exempt	$	—	$	—	$	—	$	—	$	—	$	—	$	302,905	$	302,905
Available-for-sale debt securities
CDO	$	—	$	—	$	—	$	—	$	—	$	15,327	$	—	$	15,327
Commercial MBS issued by GSEs	—		100,106		—		—		—		—		—		100,106
Corporate debt securities	—		—		—		66,515		32,865		—		—		99,380
Private label residential MBS	887,520		—		34,342		343		947		1,442		—		924,594
Residential MBS issued by GSEs	—		1,530,124		—		—		—		—		—		1,530,124
Tax-exempt	66,160		12,146		306,409		152,330		—		—		1,623		538,668
Trust preferred securities	—		—		—		—		28,617		—		—		28,617
U.S. government sponsored agency securities	—		38,188		—		—		—		—		—		38,188
U.S. treasury securities	—		1,984		—		—		—		—		—		1,984
Total AFS securities	$	953,680	$	1,682,548	$	340,751	$	219,188	$	62,429	$	16,769	$	1,623	$	3,276,988
Equity securities
CRA investments	$	—	$	25,375	$	—	$	—	$	—	$	—	$	25,767	$	51,142
Preferred stock	—		—		—		—		45,771		3,693		14,455		63,919
Total equity securities	$	—	$	25,375	$	—	$	—	$	45,771	$	3,693	$	40,222	$	115,061

(1) Where ratings differ, the Company uses an average of the available ratings by major credit agencies.

Gross Gains and (Losses) on Sales of Investment Securities

here were no gains and losses recognized on sales of these investment securities during the three and six months ended June 30, 2019 and June 30, 2018