Investment Securities Held-to-Maturity (Tables)

12 Months Ended

Dec. 31, 2019

Text Block [Abstract]

Summary of Held-to-Maturity Securities

	December 31, 2019								December 31, 2018
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
(dollars in thousands)
U.S. Treasury	$	—	$	—	$	—	$	—	$	9,960	$	—	$	2	$	9,958
U.S. Government Sponsored Enterprises		98,867		527		96		99,298		234,228		336		803		233,761
SBA Backed Securities		44,379		182		303		44,258		52,051		—		2,065		49,986
U.S. Government Sponsored Enterprises Mortgage-Backed Securities		2,207,874		20,720		10,846		2,217,748		1,750,408		2,324		55,016		1,697,716
Total	$	2,351,120	$	21,429	$	11,245	$	2,361,304	$	2,046,647	$	2,660	$	57,886	$	1,991,421

Company's Securities Held-to-Maturity

The following table shows the maturity distribution of the Company’s securities held-to-maturity at December 31, 2019.

	Amortized Cost		Fair Value
(dollars in thousands)
Within one year	$	73,576	$	73,841
After one but within five years		1,891,043		1,900,050
After five but within ten years		374,071		374,688
More than ten years		12,430		12,725
Total	$	2,351,120	$	2,361,304

Unrealized Market Loss of Securities

The following table shows the temporarily impaired securities of the Company’s held-to-maturity portfolio at December 31, 2019. This table shows the unrealized market loss of securities that have been in a continuous unrealized loss position for 12 months or less and a continuous loss position for 12 months and longer. There are 114 and 103 securities that are temporarily impaired for less than 12 months and for 12 months or longer, respectively, out of a total of 531 holdings at December 31, 2019.

Temporarily Impaired Investments	December 31, 2019
	Less Than 12 Months				12 Months or Longer				Total
	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
(dollars in thousands)
U.S. Treasury	$	—	$	—	$	—	$	—	$	—	$	—
U.S. Government Sponsored Enterprises		24,420		72		9,976		24		34,396		96
SBA Backed Securities		25,251		303		—		—		25,251		303
U.S. Government Agency and Sponsored Enterprise Mortgage-Backed Securities		613,905		3,949		389,919		6,897		1,003,824		10,846
Total temporarily impaired securities	$	663,576	$	4,324	$	399,895	$	6,921	$	1,063,471	$	11,245

The following table shows the temporarily impaired securities of the Company’s held-to-maturity portfolio at December 31, 2018.This table shows the unrealized market loss of securities that have been in a continuous unrealized loss position for 12 months or less and a continuous loss position for 12 months and longer. There are 56 and 315 securities that are temporarily impaired for less than 12 months and for 12 months or longer, respectively, out of a total of 475 holdings at December 31, 2018.

Temporarily Impaired Investments	December 31, 2018
	Less Than 12 Months				12 Months or Longer				Total
	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
(dollars in thousands)
U.S. Treasury	$	9,958	$	2	$	—	$	—	$	9,958	$	2
U.S. Government Sponsored Enterprises		9,849		42		69,499		761		79,348		803
SBA Backed Securities		—		—		49,987		2,065		49,987		2,065
U.S. Government Agency and Sponsored Enterprise Mortgage-Backed Securities		188,125		2,032		1,249,689		52,984		1,437,814		55,016
Total temporarily impaired securities	$	207,932	$	2,076	$	1,369,175	$	55,810	$	1,577,107	$	57,886