Investments (Tables)

12 Months Ended

Dec. 31, 2020

Aggregate Values And Unrealized Gains And Losses Of Investment Securities

The amortized cost and fair value of investment and marketable equity securities at December 31, 2020 and 2019, were as follows:


	December 31, 2020
(Dollars in thousands)	Cost		Gross unrealized gains		Gross unrealized losses		Allowance for credit losses		Fair value
Investment securities available for sale
U.S. Treasury	$	499,832	$	101	$	—	$	—	$	499,933
Government agency	706,241		723		5,573		—		701,391
Residential mortgage-backed securities	4,369,130		70,283		1,310		—		4,438,103
Commercial mortgage-backed securities	745,892		25,645		—		—		771,537
Corporate bonds	590,870		14,437		2,028		—		603,279

Total investment securities available for sale	$	6,911,965	$	111,189	$	8,911	$	—	$	7,014,243
Investment in marketable equity securities	84,837		8,654		1,811				91,680
Investment securities held to maturity
Residential mortgage-backed securities	1,877,692		17,689		—		—		1,895,381
Commercial mortgage-backed securities	937,034		3,884		56		—		940,862
Other	2,256		—		—		—		2,256
Total investment securities held to maturity	2,816,982		21,573		56		—		2,838,499
Total investment securities	$	9,813,784	$	141,416	$	10,778	$	—	$	9,944,422

			December 31, 2019
			Cost		Gross unrealized gains		Gross unrealized losses		Fair value
Investment securities available for sale
U.S. Treasury			$	409,397	$	602	$	—	$	409,999
Government agency			684,085		928		2,241		682,772
Residential mortgage-backed securities			5,269,060		13,417		15,387		5,267,090
Commercial mortgage-backed securities			373,105		6,974		59		380,020
Corporate bonds			198,278		3,420		132		201,566
State, county and municipal			118,227		—		—		118,227
Total investment securities available for sale			$	7,052,152	$	25,341	$	17,819	$	7,059,674
Investment in marketable equity securities			59,262		23,304		233		82,333
Investment securities held to maturity


Other			30,996		—		—		30,996

Total investment securities			$	7,142,410	$	48,645	$	18,052	$	7,173,003

Investment Securities Maturity Information

The following table provides the amortized cost and fair value by contractual maturity. Expected maturities will differ from contractual maturities on certain securities because borrowers and issuers may have the right to call or prepay obligations with or without prepayment penalties. Residential and commercial mortgage-backed and government agency securities are stated separately as they are not due at a single maturity date.


	December 31, 2020				December 31, 2019
(Dollars in thousands)	Cost		Fair value		Cost		Fair value
Investment securities available for sale
Non-amortizing securities maturing in:
One year or less	$	500,846	$	500,954	$	406,325	$	406,927
One through five years	72,565		73,881		24,496		24,971
Five through 10 years	508,320		519,570		185,209		187,868
Over 10 years	8,971		8,807		109,872		110,026
Government agency	706,241		701,391		684,085		682,772

Residential mortgage-backed securities	4,369,130		4,438,103		5,269,060		5,267,090
Commercial mortgage-backed securities	745,892		771,537		373,105		380,020
Total investment securities available for sale	$	6,911,965	$	7,014,243	$	7,052,152	$	7,059,674
Investment securities held to maturity
Non-amortizing securities maturing in:
One year or less	$	1,507	$	1,507	$	30,746	$	30,746
One through five years	749		749		250		250
Residential mortgage-backed securities	1,877,692		1,895,381		—		—
Commercial mortgage-backed securities	937,034		940,862		—		—
Total investment securities held to maturity	$	2,816,982	$	2,838,499	$	30,996	$	30,996

Securities Gains (Losses)

For each period presented, realized gains on investment securities available for sale included the following:


	Year ended December 31
(Dollars in thousands)	2020		2019		2018
Gross gains on retirement/sales of investment securities available for sale	$	60,932	$	8,993	$	353
Gross losses on sales of investment securities available for sale	(679)		(1,878)		(2)

Realized gains on investment securities available for sale, net	$	60,253	$	7,115	$	351

Schedule of Realized and Unrealized Gains or Losses on Marketable Equity Securities

realized and unrealized gains or losses on marketable equity securities included the following:


	Year ended December 31
(Dollars in thousands)	2020		2019		2018
Marketable equity securities gains (losses), net	$	29,395	$	20,625	$	(7,610)
Less net gains recognized on marketable equity securities sold	44,550		16,344		1,190
Unrealized (losses) gains recognized on marketable equity securities held	$	(15,155)	$	4,281	$	(8,800)

Investment Securities With Unrealized Losses

The following table provides information regarding investment securities with unrealized losses as of December 31, 2020 and 2019:


	December 31, 2020
	Less than 12 months				12 months or more				Total
(Dollars in thousands)	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
Investment securities available for sale

Government agency	$	268,622	$	3,197	$	328,777	$	2,376	$	597,399	$	5,573
Residential mortgage-backed securities	433,816		1,241		23,064		69		456,880		1,310

Corporate bonds	57,715		2,028		—		—		57,715		2,028

Total	$	760,153	$	6,466	$	351,841	$	2,445	$	1,111,994	$	8,911





	December 31, 2019
	Less than 12 months				12 months or more				Total
	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
Investment securities available for sale

Government agency	$	347,081	$	1,827	$	63,947	$	414	$	411,028	$	2,241
Residential mortgage-backed securities	2,387,293		14,016		264,257		1,371		2,651,550		15,387
Commercial mortgage-backed securities	35,926		59		—		—		35,926		59
Corporate bonds	7,714		123		4,749		9		12,463		132

Total	$	2,778,014	$	16,025	$	332,953	$	1,794	$	3,110,967	$	17,819