Investment Securities (Tables)

9 Months Ended

Sep. 30, 2017

Summary of Amortized Cost and Estimated Fair Values of Available for Sale Securities

The amortized cost and estimated fair values of securities available for sale are summarized as follows.

	September 30, 2017
			Gross		Gross		Estimated		Cumulative
	Amortized		Unrealized		Unrealized		Fair		OTTI in
	Cost		Gains		Losses		Value		AOCI (1)
U.S. Treasury securities and obligations of U.S. Government corporations and agencies	$	115,224	$	864	$	222	$	115,866	$	0
State and political subdivisions		305,096		2,567		2,522		305,141		0
Residential mortgage-backed securities
Agency		715,003		3,819		4,122		714,700		0
Non-agency		5,259		587		0		5,846		86
Commercial mortgage-backed securities
Agency		420,115		2,081		1,404		420,792		0
Asset-backed securities		13,422		10		3		13,429		0
Trust preferred collateralized debt obligations		38,186		317		6,844		31,659		20,770
Single issue trust preferred securities		13,404		404		1,341		12,467		0
Other corporate securities		18,998		256		0		19,254		0
Marketable equity securities		9,950		541		11		10,480		0
Total	$	1,654,657	$	11,446	$	16,469	$	1,649,634	$	20,856

	December 31, 2016
			Gross		Gross		Estimated		Cumulative
	Amortized		Unrealized		Unrealized		Fair		OTTI in
	Cost		Gains		Losses		Value		AOCI (1)
U.S. Treasury securities and obligations of U.S. Government corporations and agencies	$	95,247	$	698	$	159	$	95,786	$	0
State and political subdivisions		196,350		1,364		4,902		192,812		0
Residential mortgage-backed securities
Agency		585,208		3,999		5,111		584,096		0
Non-agency		6,629		426		12		7,043		86
Commercial mortgage-backed securities
Agency		304,635		1,948		1,242		305,341		0
Asset-backed securities		217		0		0		217		0
Trust preferred collateralized debt obligations		48,558		729		15,735		33,552		25,952
Single issue trust preferred securities		13,363		284		2,170		11,477		0
Other corporate securities		14,996		66		0		15,062		0
Marketable equity securities		12,436		1,398		6		13,828		0
Total	$	1,277,639	$	10,912	$	29,337	$	1,259,214	$	26,038

(1) Non-credit related other-than-temporary impairment in accumulated other comprehensive income. Amounts are before-tax.

Summary of Securities Available for Sale in an Unrealized Loss Position

The following is a summary of securities available-for-sale which were in an unrealized loss position at September 30, 2017 and December 31, 2016.

	Less than 12 months				12 months or longer
	Fair		Unrealized		Fair		Unrealized
	Value		Losses		Value		Losses
September 30, 2017
U.S. Treasury securities and obligations of U.S. Government corporations and agencies	$	27,053	$	128	$	19,932	$	94
State and political subdivisions		83,310		896		38,004		1,626
Residential mortgage-backed securities
Agency		351,936		3,410		31,690		712
Non-agency		0		0		0		0
Commercial mortgage-backed securities
Agency		228,307		1,218		12,272		186
Asset-backed securities		6,760		3		0		0
Trust preferred collateralized debt obligations		0		0		29,544		6,844
Single issue trust preferred securities		0		0		4,365		1,341
Marketable equity securities		0		0		352		11
Total	$	697,366	$	5,655	$	136,159	$	10,814

	Less than 12 months				12 months or longer
	Fair		Unrealized		Fair		Unrealized
	Value		Losses		Value		Losses
December 31, 2016
U.S. Treasury securities and obligations of U.S. Government corporations and agencies	$	24,101	$	159	$	0	$	0
State and political subdivisions		116,300		4,902		0		0
Residential mortgage-backed securities
Agency		309,376		5,111		0		0
Non-agency		0		0		218		12
Commercial mortgage-backed securities
Agency		162,479		1,242		0		0
Asset-backed securities		0		0		0		0
Trust preferred collateralized debt obligations		0		0		28,579		15,735
Single issue trust preferred securities		0		0		8,185		2,170
Marketable equity securities		357		6		0		0
Total	$	612,613	$	11,420	$	36,982	$	17,917

Summary of Gains or Losses on Proceeds from Maturities, Sales and Calls of Available for Sale Securities by Specific Identification Method

The realized losses relate to sales of securities within a rabbi trust for the payment of benefits under a deferred compensation plan for certain key officers of United and its subsidiaries.

	Three Months Ended September 30				Nine Months Ended September 30
	2017		2016		2017		2016
Proceeds from sales and calls	$	64,257	$	174,015	$	631,561	$	368,246
Gross realized gains		1,781		3		2,840		259
Gross realized losses		1,314		1		1,396		7

Summary of Unrealized Loss Positions of Available for Sale TRUP CDOs and Single Issue Trust Preferred Securities

The following is a summary of the available for sale Trup Cdos as of September 30, 2017:

								Amortized Cost
Class	Amortized Cost		Fair Value		Unrealized Loss			Investment Grade		Split Rated		Below Investment Grade
Senior – Bank	$	5,208	$	5,287	$	(79	)	$	3,410	$	0	$	1,798
Mezzanine – Bank (now in senior position)		6,428		5,518		910			0		0		6,428
Mezzanine – Bank		22,656		17,918		4,738			0		0		22,656
Mezzanine – Bank & Insurance (combination)		3,894		2,936		958			0		0		3,894
Totals	$	38,186	$	31,659	$	6,527		$	3,410	$	0	$	34,776

Roll Forward of Credit Losses on Securities

Below is a progression of the credit losses on securities which United has recorded other-than-temporary charges. These charges were recorded through earnings and other comprehensive income.

	Three Months Ended September 30					Nine Months Ended September 30
	2017			2016		2017			2016
Balance of cumulative credit losses at beginning of period	$	22,162		$	22,162	$	22,162		$	23,773
Additional credit losses on securities for which OTTI was previously recognized		0			0		0			33
Reductions during the period for securities for which the amount previously recognized in other comprehensive income was recognized in earnings		(4,102	)		0		(4,102	)		(1,644	)
Balance of cumulative credit losses at end of period	$	18,060		$	22,162	$	18,060		$	22,162

Summary of Amortized Cost and Estimated Fair Values of Securities Held to Maturity

The amortized cost and estimated fair values of securities held to maturity are summarized as follows:

	September 30, 2017
			Gross		Gross		Estimated
	Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value
U.S. Treasury securities and obligations of U.S. Government corporations and agencies	$	5,215	$	400	$	0	$	5,615
State and political subdivisions		5,674		12		0		5,686
Residential mortgage-backed securities
Agency		26		4		0		30
Single issue trust preferred securities		9,400		0		842		8,558
Other corporate securities		20		0		0		20
Total	$	20,335	$	416	$	842	$	19,909

	December 31, 2016
			Gross		Gross		Estimated
	Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value
U.S. Treasury securities and obligations of U.S. Government corporations and agencies	$	5,295	$	570	$	0	$	5,865
State and political subdivisions		8,598		17		0		8,615
Residential mortgage-backed securities
Agency		30		5		0		35
Single issue trust preferred securities		19,315		0		2,672		16,643
Other corporate securities		20		0		0		20
Total	$	33,258	$	592	$	2,672	$	31,178

Available-for-sale Securities [Member]

Summary of Maturities of Debt Securities Held to Maturity by Amortized Cost and Estimated Fair Value

The amortized cost and estimated fair value of securities available for sale at September 30, 2017 and December 31, 2016 by contractual maturity are shown as follows. Expected maturities may differ from contractual maturities because the issuers may have the right to call or prepay obligations without penalties.

	September 30, 2017				December 31, 2016
			Estimated				Estimated
	Amortized		Fair		Amortized		Fair
	Cost		Value		Cost		Value
Due in one year or less	$	57,720	$	57,622	$	53,286	$	53,330
Due after one year through five years		370,020		371,007		296,181		297,385
Due after five years through ten years		342,176		343,326		213,094		213,791
Due after ten years		874,791		867,199		702,642		680,880
Marketable equity securities		9,950		10,480		12,436		13,828
Total	$	1,654,657	$	1,649,634	$	1,277,639	$	1,259,214

Held-to-maturity Securities [Member]

Summary of Maturities of Debt Securities Held to Maturity by Amortized Cost and Estimated Fair Value

The amortized cost and estimated fair value of debt securities held to maturity at September 30, 2017 and December 31, 2016 by contractual maturity are shown below. Expected maturities may differ from contractual maturities because the issuers may have the right to call or prepay obligations without penalties.

	September 30, 2017				December 31, 2016
			Estimated				Estimated
	Amortized		Fair		Amortized		Fair
	Cost		Value		Cost		Value
Due in one year or less	$	0	$	0	$	1,040	$	1,041
Due after one year through five years		9,189		9,600		8,268		8,850
Due after five years through ten years		5,726		5,382		3,585		3,589
Due after ten years		5,420		4,927		20,365		17,698
Total	$	20,335	$	19,909	$	33,258	$	31,178