Impairment of Investment Securities (Tables)

12 Months Ended

Dec. 31, 2017

Impairment of Investment Securities Disclosure [Abstract]

Schedule of Unrealized Losses and Estimated Fair Values

The following table presents the gross unrealized losses and estimated fair values at December 31, 2017 for both available for sale and held to maturity securities by investment category and time frame for which the securities have been in a continuous unrealized loss position:



	Less Than 12 Months					12 Months or More					Total
	Estimated Fair Value		Gross Unrealized Losses			Estimated Fair Value		Gross Unrealized Losses			Estimated Fair Value		Gross Unrealized Losses
	(dollars in thousands)
Obligations of U.S. Government Agencies:
Mortgage-Backed Securities – Residential	$	5,584	$	(21	)	$	—	$	—		$	5,584	$	(21	)
Mortgage-Backed Securities – Commercial	48,322		(962		)	32,683		(894		)	81,005		(1,856		)
Obligations of U.S. Government-Sponsored Enterprises:
Mortgage-Backed Securities – Residential	351,222		(2,295		)	400,984		(9,746		)	752,206		(12,041		)
Mortgage-Backed Securities – Commercial	13,985		(71		)	—		—			13,985		(71		)
Other Government-Sponsored Enterprises	997		(1		)	99		—			1,096		(1		)
Obligations of States and Political Subdivisions	7,144		(32		)	3,653		(129		)	10,797		(161		)
Corporate Securities	3,993		(4		)	—		—			3,993		(4		)
Pooled Trust Preferred Collateralized Debt Obligations	—		—			19,120		(4,379		)	19,120		(4,379		)
Total Securities	$	431,247	$	(3,386	)	$	456,539	$	(15,148	)	$	887,786	$	(18,534	)

At December 31, 2017, pooled trust preferred collateralized debt obligations accounted for 24% of unrealized losses due to changes in interest rates and the illiquid market for this type of investment. Fixed income securities issued by U.S. Government-sponsored enterprises comprised 65% of total unrealized losses due to changes in market interest rates. Government agencies and obligations of state and political subdivisions each account for 10% of total unrealized losses as a result of changes in market interest rates. At December 31, 2017, there were 98 debt securities in an unrealized loss position, 30 of which related to residential mortgage-backed securities with an unrealized loss of 12 months or more. There were no equity securities in an unrealized loss position at December 31, 2017.

The following table presents the gross unrealized losses and estimated fair value at December 31, 2016 for both available for sale and held to maturity securities by investment category and time frame for which the securities had been in a continuous unrealized loss position:



	Less Than 12 Months					12 Months or More					Total
	Estimated Fair Value		Gross Unrealized Losses			Estimated Fair Value		Gross Unrealized Losses			Estimated Fair Value		Gross Unrealized Losses
	(dollars in thousands)
Obligations of U.S. Government Agencies:
Mortgage-Backed Securities – Residential	$	4,898	$	(11	)	$	—	$	—		$	4,898	$	(11	)
Mortgage-Backed Securities – Commercial	33,883		(561		)	—		—			33,883		(561		)
Obligations of U.S. Government-Sponsored Enterprises:
Mortgage-Backed Securities – Residential	670,708		(11,630		)	56,200		(2,202		)	726,908		(13,832		)
Mortgage-Backed Securities – Commercial	14,534		(142		)	—		—			14,534		(142		)
Other Government-Sponsored Enterprises	16,632		(69		)	—		—			16,632		(69		)
Obligations of States and Political Subdivisions	33,277		(762		)	—		—			33,277		(762		)
Pooled Trust Preferred Collateralized Debt Obligations	—		—			28,952		(7,124		)	28,952		(7,124		)
Total Securities	$	773,932	$	(13,175	)	$	85,152	$	(9,326	)	$	859,084	$	(22,501	)

Pooled Trust Preferred Collateralized Debt Obligations

The following table provides additional information related to our pooled trust preferred collateralized debt obligations as of December 31, 2017:



Deal	Class	Book Value		Estimated Fair Value		Unrealized Gain (Loss)			Moody’s/ Fitch Ratings	Number of Banks	Deferrals and Defaults as a % of Current Collateral		Excess Subordination as a % of Current Performing Collateral
(dollars in thousands)
PreTSL IV	Mezzanine	$	1,817	$	1,405	$	(412	)	Ba1/BB	6	18.05	%	72.13	%
PreTSL VIII	Mezzanine	2,043		2,228		185			C/C	26	38.52		0.00
PreTSL IX	Mezzanine	2,448		2,052		(396		)	B1/C	37	27.83		19.46
PreTSL X	Mezzanine	1,863		2,125		262			Caa1/C	41	27.93		1.62
PreTSL XII	Mezzanine	6,097		5,209		(888		)	B3/C	63	23.35		0.00
PreTSL XIV	Mezzanine	13,136		10,453		(2,683		)	Ba2/CCC	49	12.95		39.26
MMCap I	Mezzanine	95		174		79			Ca/C	7	69.35		69.99
Total		$	27,499	$	23,646	$	(3,853	)

Cumulative Roll Forward of Credit Losses Recognized in Earnings for Debt Securities Held and Not Intended to be Sold

The table below provides a cumulative roll forward of credit losses recognized in earnings for debt securities held and not intended to be sold for the years ended December 31:



	2017			2016			2015
	(dollars in thousands)
Balance, beginning (a)	$	17,056		$	24,851		$	26,246
Credit losses on debt securities for which other-than-temporary impairment was not previously recognized	—			—			—
Additional credit losses on debt securities for which other-than-temporary impairment was previously recognized	—			—			—
Increases in cash flows expected to be collected, recognized over the remaining life of the security (b)	(890		)	(1,124		)	(1,177		)
Reduction for debt securities called during the period	(3,958		)	(6,671		)	(218		)
Balance, ending	$	12,208		$	17,056		$	24,851


(a)	The beginning balance represents credit related losses included in other-than-temporary impairment charges recognized on debt securities in prior periods.


(b)	Represents the increase in cash flows recognized either as principal payments or interest income during the period.