12. Accumulated Other Comprehensive Income (Loss)

Accumulated other comprehensive income (loss) is defined as the change in stockholders’ equity from all transactions other than those with stockholders, and is comprised of net income and other comprehensive income (loss). The Company’s significant items of accumulated other comprehensive income (loss) are pension and other benefits, net unrealized gains or losses on investment securities and net unrealized gains or losses on cash flow derivative hedges. Changes in accumulated other comprehensive income (loss) for the years ended December 31, 2017, 2016 and 2015 are presented below:


			Income
			Tax
	Pre-tax		Benefit		Net of
(dollars in thousands)	Amount		(Expense)		Tax
Accumulated other comprehensive loss at December 31, 2016	$	(145,472)	$	57,461	$	(88,011)
Year ended December 31, 2017
Pension and other benefits:
Net actuarial losses arising during the year		(1,104)		436		(668)
Prior service credit		(429)		170		(259)
Amortization of net loss included in net income		8,625		(3,407)		5,218
Net change in pension and other benefits		7,092		(2,801)		4,291
Investment securities:
Unrealized net losses arising during the year		(23,516)		9,357		(14,159)
Net change in unrealized losses on investment securities		(23,516)		9,357		(14,159)
Cash flow derivative hedges:
Unrealized net gains on cash flow derivative hedges arising during the year		2,473		(977)		1,496
Net change in unrealized gains on cash flow derivative hedges		2,473		(977)		1,496
Other comprehensive loss		(13,951)		5,579		(8,372)
Accumulated other comprehensive loss at December 31, 2017	$	(159,423)	$	63,040	$	(96,383)


			Income
			Tax
	Pre-tax		Benefit		Net of
(dollars in thousands)	Amount		(Expense)		Tax
Accumulated other comprehensive loss at December 31, 2015	$	(84,722)	$	33,463	$	(51,259)
Year ended December 31, 2016
Pension and other benefits:
Net actuarial losses arising during the year		(12,666)		5,004		(7,662)
Prior service credit		(429)		169		(260)
Amortization of net loss included in net income		7,629		(3,012)		4,617
Change due to Reorganization Transactions		(81)		32		(49)
Net change in pension and other benefits		(5,547)		2,193		(3,354)
Investment securities:
Unrealized net losses arising during the year		(30,323)		11,974		(18,349)
Reclassification of net gains to net income:
Investment securities gains, net		(27,277)		10,774		(16,503)
Net change in unrealized losses on investment securities		(57,600)		22,748		(34,852)
Cash flow derivative hedges:
Unrealized net gains on cash flow derivative hedges arising during the year		2,397		(943)		1,454
Net change in unrealized gains on cash flow derivative hedges		2,397		(943)		1,454
Other comprehensive loss		(60,750)		23,998		(36,752)
Accumulated other comprehensive loss at December 31, 2016	$	(145,472)	$	57,461	$	(88,011)


			Income
			Tax
	Pre-tax		Benefit		Net of
(dollars in thousands)	Amount		(Expense)		Tax
Accumulated other comprehensive loss at December 31, 2014	$	(85,048)	$	33,591	$	(51,457)
Year ended December 31, 2015
Pension and other benefits:
Net actuarial gains arising during the year		5,322		(2,102)		3,220
Prior service credit		(429)		169		(260)
Amortization of net loss included in net income		9,960		(3,934)		6,026
Net change in pension and other benefits		14,853		(5,867)		8,986
Investment securities:
Unrealized net losses arising during the year		(3,503)		1,384		(2,119)
Reclassification of net gains to net income:
Investment securities gains, net		(12,321)		4,867		(7,454)
Net change in unrealized losses on investment securities		(15,824)		6,251		(9,573)
Cash flow derivative hedges:
Unrealized net gains on cash flow derivative hedges arising during the year		1,684		(665)		1,019
Reclassification of net realized gains included in net income		(387)		153		(234)
Net change in unrealized gains on cash flow derivative hedges		1,297		(512)		785
Other comprehensive income		326		(128)		198
Accumulated other comprehensive loss at December 31, 2015	$	(84,722)	$	33,463	$	(51,259)

The following table summarizes changes in accumulated other comprehensive loss, net of tax, for the years indicated:


					Unrealized		Total
	Pensions		Unrealized		Gains		Accumulated
	and		Losses		(Losses) on		Other
	Other		on Investment		Cash Flow		Comprehensive
(dollars in thousands)	Benefits		Securities		Derivative Hedges		Loss
Year Ended December 31, 2017
Balance at beginning of year	$	(30,237)	$	(59,958)	$	2,184	$	(88,011)
Other comprehensive income (loss)		4,291		(14,159)		1,496		(8,372)
Balance at end of year	$	(25,946)	$	(74,117)	$	3,680	$	(96,383)

Year Ended December 31, 2016
Balance at beginning of year	$	(26,883)	$	(25,106)	$	730	$	(51,259)
Other comprehensive income (loss)		(3,354)		(34,852)		1,454		(36,752)
Balance at end of year	$	(30,237)	$	(59,958)	$	2,184	$	(88,011)

Year Ended December 31, 2015
Balance at beginning of year	$	(35,869)	$	(15,533)	$	(55)	$	(51,457)
Other comprehensive income (loss)		8,986		(9,573)		785		198
Balance at end of year	$	(26,883)	$	(25,106)	$	730	$	(51,259)

At December 31, 2017 and 2016, there were no non-credit other-than-temporary impairment losses on securities available for sale.