Loans and Allowances for Credit Losses (Tables)

3 Months Ended

Mar. 31, 2017

Loans Receivable, Net [Abstract]

Schedule of Loans by Portfolio Segment [Table Text Block]

Portfolio segments of the loan portfolio are as follows (in thousands):

	March 31, 2017								December 31, 2016
	Fixed Rate		Variable Rate		Non-accrual		Total		Fixed Rate		Variable Rate		Non-accrual		Total
Commercial	$	2,201,040	$	7,969,245	$	156,825	$	10,327,110	$	2,327,085	$	7,884,786	$	178,953	$	10,390,824
Commercial real estate	590,375		3,276,213		4,475		3,871,063		624,187		3,179,338		5,521		3,809,046
Residential mortgage	1,616,328		283,865		46,081		1,946,274		1,647,357		256,255		46,220		1,949,832
Personal	149,312		697,912		235		847,459		154,971		684,697		290		839,958
Total	$	4,557,055	$	12,227,235	$	207,616	$	16,991,906	$	4,753,600	$	12,005,076	$	230,984	$	16,989,660
Accruing loans past due (90 days)1							$	95							$	5

	March 31, 2016
	Fixed Rate		Variable Rate		Non-accrual		Total
Commercial	$	1,932,757	$	8,181,016	$	174,652	$	10,288,425
Commercial real estate	643,033		2,718,204		9,270		3,370,507
Residential mortgage	1,592,706		219,026		57,577		1,869,309
Personal	87,092		406,902		331		494,325
Total	$	4,255,588	$	11,525,148	$	241,830	$	16,022,566
Accruing loans past due (90 days)1							$	8,019

¹  Excludes residential mortgage loans guaranteed by agencies of the U.S. government

Rollforward of Allowance For Loan Losses And Accrual for Off-Balance Sheet Credit Losses [Table Text Block]

The activity in the allowance for loan losses and the allowance for off-balance sheet credit losses related to loan commitments and standby letters of credit for the three months ended March 31, 2017 is summarized as follows (in thousands):

	Commercial			Commercial Real Estate			Residential Mortgage			Personal			Nonspecific Allowance			Total
Allowance for loan losses:
Beginning balance	$	140,213		$	50,749		$	18,224		$	8,773		$	28,200		$	246,159
Provision for loan losses	(3,355		)	6,859			(39		)	(788		)	(873		)	1,804
Loans charged off	(424		)	—			(236		)	(1,493		)	—			(2,153		)
Recoveries	1,182			735			228			755			—			2,900
Ending balance	$	137,616		$	58,343		$	18,177		$	7,247		$	27,327		$	248,710
Allowance for off-balance sheet credit losses:
Beginning balance	$	11,063		$	123		$	50		$	8		$	—		$	11,244
Provision for off-balance sheet credit losses	(1,775		)	(17		)	(10		)	(2		)	—			(1,804		)
Ending balance	$	9,288		$	106		$	40		$	6		$	—		$	9,440
Total provision for credit losses	$	(5,130	)	$	6,842		$	(49	)	$	(790	)	$	(873	)	$	—

The activity in the allowance for loan losses and the allowance for off-balance sheet credit losses related to loan commitments and standby letters of credit for the three months ended March 31, 2016 is summarized as follows (in thousands):

	Commercial			Commercial Real Estate		Residential Mortgage			Personal			Nonspecific Allowance			Total
Allowance for loan losses:
Beginning balance	$	130,334		$	41,391	$	19,509		$	4,164		$	30,126		$	225,524
Provision for loan losses	31,097			2,977		(731		)	1,466			(4,705		)	30,104
Loans charged off	(22,126		)	—		(474		)	(1,391		)	—			(23,991		)
Recoveries	488			85		163			783			—			1,519
Ending balance	$	139,793		$	44,453	$	18,467		$	5,022		$	25,421		$	233,156
Allowance for off-balance sheet credit losses:
Beginning balance	$	1,506		$	153	$	30		$	22		$	—		$	1,711
Provision for off-balance sheet credit losses	4,813			75		28			(20		)	—			4,896
Ending balance	$	6,319		$	228	$	58		$	2		$	—		$	6,607
Total provision for credit losses	$	35,910		$	3,052	$	(703	)	$	1,446		$	(4,705	)	$	35,000

The allowance for loan losses and recorded investment of the related loans by portfolio segment for each impairment measurement method at March 31, 2017 is as follows (in thousands):

	Collectively Measured for Impairment				Individually Measured for Impairment				Total
	Recorded Investment		Related Allowance		Recorded Investment		Related Allowance		Recorded Investment		Related Allowance
Commercial	$	10,170,285	$	134,164	$	156,825	$	3,452	$	10,327,110	$	137,616
Commercial real estate	3,866,588		58,343		4,475		—		3,871,063		58,343
Residential mortgage	1,900,193		18,132		46,081		45		1,946,274		18,177
Personal	847,224		7,247		235		—		847,459		7,247
Total	16,784,290		217,886		207,616		3,497		16,991,906		221,383
Nonspecific allowance	—		—		—		—		—		27,327
Total	$	16,784,290	$	217,886	$	207,616	$	3,497	$	16,991,906	$	248,710

The allowance for loan losses and recorded investment of the related loans by portfolio segment for each impairment measurement method at December 31, 2016 is as follows (in thousands):

	Collectively Measured for Impairment				Individually Measured for Impairment				Total
	Recorded Investment		Related Allowance		Recorded Investment		Related Allowance		Recorded Investment		Related Allowance
Commercial	$	10,211,871	$	139,416	$	178,953	$	797	$	10,390,824	$	140,213
Commercial real estate	3,803,525		50,749		5,521		—		3,809,046		50,749
Residential mortgage	1,903,612		18,178		46,220		46		1,949,832		18,224
Personal	839,668		8,773		290		—		839,958		8,773
Total	16,758,676		217,116		230,984		843		16,989,660		217,959
Nonspecific allowance	—		—		—		—		—		28,200
Total	$	16,758,676	$	217,116	$	230,984	$	843	$	16,989,660	$	246,159

The allowance for loan losses and recorded investment of the related loans by portfolio segment for each impairment measurement method at March 31, 2016 is as follows (in thousands):

	Collectively Measured for Impairment				Individually Measured for Impairment				Total
	Recorded Investment		Related Allowance		Recorded Investment		Related Allowance		Recorded Investment		Related Allowance
Commercial	$	10,113,773	$	137,191	$	174,652	$	2,602	$	10,288,425	$	139,793
Commercial real estate	3,361,237		44,435		9,270		18		3,370,507		44,453
Residential mortgage	1,811,732		18,401		57,577		66		1,869,309		18,467
Personal	493,994		5,022		331		—		494,325		5,022
Total	15,780,736		205,049		241,830		2,686		16,022,566		207,735
Nonspecific allowance	—		—		—		—		—		25,421
Total	$	15,780,736	$	205,049	$	241,830	$	2,686	$	16,022,566	$	233,156

Schedule of Allowance for Loan Losses and Recorded Investment by Portfolio Segment for Risk Graded and Non-Risk Graded Loans [Table Text Block]

The allowance for loan losses and recorded investment of the related loans by portfolio segment for risk graded and non-risk graded loans at March 31, 2017 is as follows (in thousands):

	Internally Risk Graded				Non-Graded				Total
	Recorded Investment		Related Allowance		Recorded Investment		Related Allowance		Recorded Investment		Related Allowance
Commercial	$	10,302,774	$	136,672	$	24,336	$	944	$	10,327,110	$	137,616
Commercial real estate	3,871,063		58,343		—		—		3,871,063		58,343
Residential mortgage	211,846		2,958		1,734,428		15,219		1,946,274		18,177
Personal	749,028		5,136		98,431		2,111		847,459		7,247
Total	15,134,711		203,109		1,857,195		18,274		16,991,906		221,383
Nonspecific allowance	—		—		—		—		—		27,327
Total	$	15,134,711	$	203,109	$	1,857,195	$	18,274	$	16,991,906	$	248,710

The allowance for loan losses and recorded investment of the related loans by portfolio segment for risk graded and non-risk graded loans at December 31, 2016 is as follows (in thousands):

	Internally Risk Graded				Non-Graded				Total
	Recorded Investment		Related Allowance		Recorded Investment		Related Allowance		Recorded Investment		Related Allowance
Commercial	$	10,360,725	$	139,293	$	30,099	$	920	$	10,390,824	$	140,213
Commercial real estate	3,809,046		50,749		—		—		3,809,046		50,749
Residential mortgage	243,703		2,893		1,706,129		15,331		1,949,832		18,224
Personal	744,602		5,035		95,356		3,738		839,958		8,773
Total	15,158,076		197,970		1,831,584		19,989		16,989,660		217,959
Nonspecific allowance	—		—		—		—		—		28,200
Total	$	15,158,076	$	197,970	$	1,831,584	$	19,989	$	16,989,660	$	246,159

The allowance for loan losses and recorded investment of the related loans by portfolio segment for risk graded and non-risk graded loans at March 31, 2016 is as follows (in thousands):

	Internally Risk Graded				Non-Graded				Total
	Recorded Investment		Related Allowance		Recorded Investment		Related Allowance		Recorded Investment		Related Allowance
Commercial	$	10,264,965	$	138,887	$	23,460	$	906	$	10,288,425	$	139,793
Commercial real estate	3,370,507		44,453		—		—		3,370,507		44,453
Residential mortgage	192,658		2,822		1,676,651		15,645		1,869,309		18,467
Personal	410,318		2,954		84,007		2,068		494,325		5,022
Total	14,238,448		189,116		1,784,118		18,619		16,022,566		207,735
Nonspecific allowance	—		—		—		—		—		25,421
Total	$	14,238,448	$	189,116	$	1,784,118	$	18,619	$	16,022,566	$	233,156

Schedule of Credit Quality Indicators [Table Text Block]

The following table summarizes the Company’s loan portfolio at March 31, 2017 by the risk grade categories (in thousands): 

	Internally Risk Graded								Non-Graded
	Performing
	Pass		Other Loans Especially Mentioned		Accruing Substandard		Nonaccrual		Performing		Nonaccrual		Total
Commercial:
Energy	$	1,988,392	$	144,157	$	294,138	$	110,425	$	—	$	—	$	2,537,112
Services	2,960,912		13,931		30,819		7,713		—		—		3,013,375
Wholesale/retail	1,459,703		21,970		13,480		11,090		—		—		1,506,243
Manufacturing	504,824		1,917		30,782		5,907		—		—		543,430
Healthcare	2,196,517		35,704		32,474		909		—		—		2,265,604
Other commercial and industrial	407,317		4,641		4,315		20,737		24,292		44		461,346
Total commercial	9,517,665		222,320		406,008		156,781		24,292		44		10,327,110
Commercial real estate:
Residential construction and land development	132,127		—		1,251		2,616		—		—		135,994
Retail	738,978		5,754		—		314		—		—		745,046
Office	857,582		2,894		—		413		—		—		860,889
Multifamily	918,542		—		4,425		24		—		—		922,991
Industrial	871,387		—		—		76		—		—		871,463
Other commercial real estate	333,554		—		94		1,032		—		—		334,680
Total commercial real estate	3,852,170		8,648		5,770		4,475		—		—		3,871,063
Residential mortgage:
Permanent mortgage	207,886		1,710		490		1,760		743,469		22,428		977,743
Permanent mortgages guaranteed by U.S. government agencies	—		—		—		—		194,073		10,108		204,181
Home equity	—		—		—		—		752,565		11,785		764,350
Total residential mortgage	207,886		1,710		490		1,760		1,690,107		44,321		1,946,274
Personal	748,000		49		888		91		98,287		144		847,459
Total	$	14,325,721	$	232,727	$	413,156	$	163,107	$	1,812,686	$	44,509	$	16,991,906

The following table summarizes the Company’s loan portfolio at December 31, 2016 by the risk grade categories (in thousands): 

	Internally Risk Graded								Non-Graded
	Performing
	Pass		Other Loans Especially Mentioned		Accruing Substandard		Nonaccrual		Performing		Nonaccrual		Total
Commercial:
Energy	$	1,937,790	$	119,583	$	307,996	$	132,499	$	—	$	—	$	2,497,868
Services	3,052,002		10,960		37,855		8,173		—		—		3,108,990
Wholesale/retail	1,535,463		16,886		13,062		11,407		—		—		1,576,818
Manufacturing	468,314		26,532		15,198		4,931		—		—		514,975
Healthcare	2,140,458		44,472		16,161		825		—		—		2,201,916
Other commercial and industrial	433,789		5,309		—		21,060		30,041		58		490,257
Total commercial	9,567,816		223,742		390,272		178,895		30,041		58		10,390,824
Commercial real estate:
Residential construction and land development	131,630		—		470		3,433		—		—		135,533
Retail	756,418		4,745		399		326		—		—		761,888
Office	798,462		—		—		426		—		—		798,888
Multifamily	898,800		—		4,434		38		—		—		903,272
Industrial	871,673		—		—		76		—		—		871,749
Other commercial real estate	336,488		—		6		1,222		—		—		337,716
Total commercial real estate	3,793,471		4,745		5,309		5,521		—		—		3,809,046
Residential mortgage:
Permanent mortgage	238,769		1,186		2,331		1,417		741,679		21,438		1,006,820
Permanent mortgages guaranteed by U.S. government agencies	—		—		—		—		187,541		11,846		199,387
Home equity	—		—		—		—		732,106		11,519		743,625
Total residential mortgage	238,769		1,186		2,331		1,417		1,661,326		44,803		1,949,832
Personal	743,451		—		1,054		97		95,163		193		839,958
Total	$	14,343,507	$	229,673	$	398,966	$	185,930	$	1,786,530	$	45,054	$	16,989,660

The following table summarizes the Company’s loan portfolio at March 31, 2016 by the risk grade categories (in thousands): 

	Internally Risk Graded								Non-Graded
	Performing
	Pass		Other Loans Especially Mentioned		Accruing Substandard		Nonaccrual		Performing		Nonaccrual		Total
Commercial:
Energy	$	2,197,870	$	269,039	$	402,958	$	159,553	$	—	$	—	$	3,029,420
Services	2,706,395		6,099		6,885		9,512		—		—		2,728,891
Wholesale/retail	1,415,832		12,383		19,946		3,685		—		—		1,451,846
Manufacturing	567,618		21,209		11,506		312		—		—		600,645
Healthcare	1,970,331		16,267		7,804		1,023		—		—		1,995,425
Other commercial and industrial	453,173		5,082		—		483		23,376		84		482,198
Total commercial	9,311,219		330,079		449,099		174,568		23,376		84		10,288,425
Commercial real estate:
Residential construction and land development	164,931		1,306		923		4,789		—		—		171,949
Retail	802,796		6,004		420		1,302		—		—		810,522
Office	694,670		253		—		629		—		—		695,552
Multifamily	726,933		—		6,506		250		—		—		733,689
Industrial	564,391		—		—		76		—		—		564,467
Other commercial real estate	392,095		—		9		2,224		—		—		394,328
Total commercial real estate	3,345,816		7,563		7,858		9,270		—		—		3,370,507
Residential mortgage:
Permanent mortgage	185,963		1,203		3,146		2,346		730,596		25,151		948,405
Permanent mortgages guaranteed by U.S. government agencies	—		—		—		—		177,800		19,550		197,350
Home equity	—		—		—		—		713,024		10,530		723,554
Total residential mortgage	185,963		1,203		3,146		2,346		1,621,420		55,231		1,869,309
Personal	410,094		1		100		123		83,799		208		494,325
Total	$	13,253,092	$	338,846	$	460,203	$	186,307	$	1,728,595	$	55,523	$	16,022,566

Summary of Impaired Loans [Table Text Block]

Impaired Loans

Loans are considered to be impaired when it is probable that the Company will not be able to collect all amounts due according to the contractual terms of the loan agreement. This includes all nonaccruing loans, all loans modified in a TDR and all loans repurchased from GNMA pools.

A summary of impaired loans follows (in thousands):

	As of										For the
	March 31, 2017										Three Months Ended
			Recorded Investment								March 31, 2017
	Unpaid Principal Balance		Total		With No Allowance		With Allowance		Related Allowance		Average Recorded Investment		Interest Income Recognized
Commercial:
Energy	$	125,579	$	110,425	$	58,324	$	52,101	$	3,435	$	121,462	$	—
Services	11,542		7,713		7,713		—		—		7,943		—
Wholesale/retail	17,582		11,090		11,090		—		—		11,248		—
Manufacturing	6,377		5,907		5,907		—		—		5,419		—
Healthcare	1,379		909		909		—		—		867		—
Other commercial and industrial	28,876		20,781		20,764		17		17		20,950		—
Total commercial	191,335		156,825		104,707		52,118		3,452		167,889		—
Commercial real estate:
Residential construction and land development	4,126		2,616		2,616		—		—		3,024		—
Retail	523		314		314		—		—		320		—
Office	515		413		413		—		—		420		—
Multifamily	1,000		24		24		—		—		31		—
Industrial	76		76		76		—		—		76		—
Other real estate loans	1,213		1,032		1,032		—		—		1,127		—
Total commercial real estate	7,453		4,475		4,475		—		—		4,998		—
Residential mortgage:
Permanent mortgage	29,355		24,188		24,143		45		45		23,521		291
Permanent mortgage guaranteed by U.S. government agencies1	210,237		204,181		204,181		—		—		207,396		1,904
Home equity	13,008		11,785		11,785		—		—		11,652		—
Total residential mortgage	252,600		240,154		240,109		45		45		242,569		2,195
Personal	265		235		235		—		—		262		—
Total	$	451,653	$	401,689	$	349,526	$	52,163	$	3,497	$	415,718	$	2,195

¹  All permanent mortgage loans guaranteed by U.S. government agencies are considered impaired as we do not expect full collection of contractual principal and interest. At March 31, 2017, $10 million of these loans were nonaccruing and $194 million were accruing based on the guarantee by U.S. government agencies.

Generally, no interest income is recognized on impaired loans until all principal balances, including amounts charged-off, are recovered.

A summary of impaired loans at December 31, 2016 follows (in thousands): 

			Recorded Investment
	Unpaid Principal Balance		Total		With No Allowance		With Allowance		Related Allowance
Commercial:
Energy	$	146,897	$	132,499	$	121,418	$	11,081	$	762
Services	11,723		8,173		8,173		—		—
Wholesale/retail	17,669		11,407		11,407		—		—
Manufacturing	5,320		4,931		4,931		—		—
Healthcare	1,147		825		825		—		—
Other commercial and industrial	29,006		21,118		21,083		35		35
Total commercial	211,762		178,953		167,837		11,116		797
Commercial real estate:
Residential construction and land development	4,951		3,433		3,433		—		—
Retail	530		326		326		—		—
Office	521		426		426		—		—
Multifamily	1,000		38		38		—		—
Industrial	76		76		76		—		—
Other real estate loans	7,349		1,222		1,222		—		—
Total commercial real estate	14,427		5,521		5,521		—		—
Residential mortgage:
Permanent mortgage	28,830		22,855		22,809		46		46
Permanent mortgage guaranteed by U.S. government agencies1	205,564		199,387		199,387		—		—
Home equity	12,611		11,519		11,519		—		—
Total residential mortgage	247,005		233,761		233,715		46		46
Personal	332		290		290		—		—
Total	$	473,526	$	418,525	$	407,363	$	11,162	$	843

¹  All permanent mortgage loans guaranteed by U.S. government agencies are considered impaired as we do not expect full collection of contractual principal and interest. At December 31, 2016, $12 million of these loans were nonaccruing and $188 million were accruing based on the guarantee by U.S. government agencies.

A summary of impaired loans at March 31, 2016 follows (in thousands): 

											For the
	As of March 31, 2016										Three Months Ended
			Recorded Investment								March 31, 2016
	Unpaid Principal Balance		Total		With No Allowance		With Allowance		Related Allowance		Average Recorded Investment		Interest Income Recognized
Commercial:
Energy	$	182,224	$	159,553	$	125,072	$	34,481	$	2,558	$	93,627	$	—
Services	12,824		9,512		9,512		—		—		9,901		—
Wholesale/retail	9,502		3,685		3,673		12		9		3,302		—
Manufacturing	658		312		312		—		—		322		—
Healthcare	1,338		1,023		905		118		35		1,048		—
Other commercial and industrial	8,235		567		567		—		—		595		—
Total commercial	214,781		174,652		140,041		34,611		2,602		108,795		—
Commercial real estate:
Residential construction and land development	7,621		4,789		4,789		—		—		4,599		—
Retail	1,923		1,302		1,302		—		—		1,311		—
Office	920		629		629		—		—		640		—
Multifamily	1,192		250		250		—		—		262		—
Industrial	76		76		76		—		—		76		—
Other real estate loans	8,348		2,224		2,068		156		18		2,248		—
Total commercial real estate	20,080		9,270		9,114		156		18		9,136		—
Residential mortgage:
Permanent mortgage	35,149		27,497		27,383		114		66		28,240		327
Permanent mortgage guaranteed by U.S. government agencies1	203,396		197,350		197,350		—		—		199,697		1,772
Home equity	11,321		10,530		10,530		—		—		10,443		—
Total residential mortgage	249,866		235,377		235,263		114		66		238,380		2,099
Personal	363		331		331		—		—		397		—
Total	$	485,090	$	419,630	$	384,749	$	34,881	$	2,686	$	356,708	$	2,099

¹  All permanent mortgage loans guaranteed by U.S. government agencies are considered impaired as we do not expect full collection of contractual principal and interest. At March 31, 2016, $20 million of these loans were nonaccruing and $178 million were accruing based on the guarantee by U.S. government agencies.

Troubled Debt Restructurings [Table Text Block]

Troubled Debt Restructurings

A summary of troubled debt restructurings ("TDRs") by accruing status as of March 31, 2017 is as follows (in thousands):

	As of March 31, 2017								Amounts Charged Off During the Three Months Ended March 31, 2017
	Recorded Investment		Performing in Accordance With Modified Terms		Not Performing in Accordance With Modified Terms		Specific Allowance
Nonaccruing TDRs:
Commercial:
Energy	$	28,529	$	22,883	$	5,646	$	271	$	—
Services	7,356		6,679		677		—		—
Wholesale/retail	10,984		10,984		—		—		—
Manufacturing	209		209		—		—		—
Healthcare	601		—		601		—		—
Other commercial and industrial	314		44		270		—		—
Total commercial	47,993		40,799		7,194		271		—
Commercial real estate:
Residential construction and land development	630		272		358		—		—
Retail	314		314		—		—		—
Office	138		138		—		—		—
Multifamily	—		—		—		—		—
Industrial	—		—		—		—		—
Other real estate loans	377		377		—		—		—
Total commercial real estate	1,459		1,101		358		—		—
Residential mortgage:
Permanent mortgage	14,457		9,876		4,581		45		—
Permanent mortgage guaranteed by U.S. government agencies	6,189		1,597		4,592		—		—
Home equity	5,663		4,236		1,427		—		20
Total residential mortgage	26,309		15,709		10,600		45		20
Personal	203		203		—		—		1
Total nonaccruing TDRs	$	75,964	$	57,812	$	18,152	$	316	$	21
Accruing TDRs:
Permanent mortgages guaranteed by U.S. government agencies	83,577		29,040		54,537		—		—
Total TDRs	$	159,541	$	86,852	$	72,689	$	316	$	21

A summary of troubled debt restructurings by accruing status as of December 31, 2016 is as follows (in thousands):

	As of
	December 31, 2016
	Recorded Investment		Performing in Accordance With Modified Terms		Not Performing in Accordance With Modified Terms		Specific Allowance
Nonaccruing TDRs:
Commercial:
Energy	$	16,893	$	10,867	$	6,026	$	—
Services	7,527		6,830		697		—
Wholesale/retail	11,291		11,251		40		—
Manufacturing	224		224		—		—
Healthcare	607		—		607		—
Other commercial and industrial	337		53		284		—
Total commercial	36,879		29,225		7,654		—
Commercial real estate:
Residential construction and land development	690		97		593		—
Retail	326		326		—		—
Office	143		143		—		—
Multifamily	—		—		—		—
Industrial	—		—		—		—
Other real estate loans	548		548		—		—
Total commercial real estate	1,707		1,114		593		—
Residential mortgage:
Permanent mortgage	14,876		10,175		4,701		46
Permanent mortgage guaranteed by U.S. government agencies	6,702		2,241		4,461		—
Home equity	5,346		4,458		888		—
Total residential mortgage	26,924		16,874		10,050		46
Personal	237		236		1		—
Total nonaccuring TDRs	$	65,747	$	47,449	$	18,298	$	46
Accruing TDRs:
Permanent mortgages guaranteed by U.S. government agencies	81,370		27,289		54,081		—
Total TDRs	$	147,117	$	74,738	$	72,379	$	46

A summary of troubled debt restructurings by accruing status as of March 31, 2016 is as follows (in thousands):

	As of March 31, 2016								Amounts Charged Off During the Three Months Ended March 31, 2016
	Recorded Investment		Performing in Accordance With Modified Terms		Not Performing in Accordance With Modified Terms		Specific Allowance
Nonaccruing TDRs:
Commercial:
Energy	$	2,829	$	—	$	2,829	$	—	$	—
Services	8,863		8,076		787		—		—
Wholesale/retail	2,619		2,567		52		9		—
Manufacturing	267		267		—		—		—
Healthcare	656		656		—		—		—
Other commercial and industrial	548		65		483		—		57
Total commercial	15,782		11,631		4,151		9		57
Commercial real estate:
Residential construction and land development	1,871		296		1,575		—		—
Retail	1,302		925		377		—		—
Office	160		160		—		—		—
Multifamily	—		—		—		—		—
Industrial	—		—		—		—		—
Other real estate loans	909		478		431		—		—
Total commercial real estate	4,242		1,859		2,383		—		—
Residential mortgage:
Permanent mortgage	16,242		11,451		4,791		66		3
Permanent mortgage guaranteed by U.S. government agencies	9,809		851		8,958		—		—
Home equity	5,078		4,207		871		—		66
Total residential mortgage	31,129		16,509		14,620		66		69
Personal	284		262		22		—		7
Total nonaccruing TDRs	$	51,437	$	30,261	$	21,176	$	75	$	133
Accruing TDRs:
Permanent mortgages guaranteed by U.S. government agencies	77,598		28,415		49,183		—		—
Total TDRs	$	129,035	$	58,676	$	70,359	$	75	$	133

Troubled debt restructurings generally consist of interest rate concessions, payment stream concessions or a combination of concessions to distressed borrowers. The following tables detail the recorded balance of loans at March 31, 2017 by class that were restructured during the three months ended March 31, 2017 by primary type of concession (in thousands):

	Three Months Ended March 31, 2017
	Accruing						Nonaccrual						Total
	Payment Stream		Combination & Other		Total		Payment Stream		Combination & Other		Total
Commercial:
Energy	$	—	$	—	$	—	$	13,242	$	—	$	13,242	$	13,242
Services	—		—		—		—		—		—		—
Wholesale/retail	—		—		—		—		—		—		—
Manufacturing	—		—		—		—		—		—		—
Healthcare	—		—		—		—		—		—		—
Other commercial and industrial	—		—		—		—		—		—		—
Total commercial	—		—		—		13,242		—		13,242		13,242
Commercial real estate:
Residential construction and land development	—		—		—		—		—		—		—
Retail	—		—		—		—		—		—		—
Office	—		—		—		—		—		—		—
Multifamily	—		—		—		—		—		—		—
Industrial	—		—		—		—		—		—		—
Other real estate loans	—		—		—		—		—		—		—
Total commercial real estate	—		—		—		—		—		—		—
Residential mortgage:
Permanent mortgage	—		—		—		16		31		47		47
Permanent mortgage guaranteed by U.S. government agencies	5,885		2,027		7,912		—		181		181		8,093
Home equity	—		—		—		124		531		655		655
Total residential mortgage	5,885		2,027		7,912		140		743		883		8,795
Personal	—		—		—		—		4		4		4
Total	$	5,885	$	2,027	$	7,912	$	13,382	$	747	$	14,129	$	22,041

Troubled debt restructurings generally consist of interest rate concessions, payment stream concessions or a combination of concessions to distressed borrowers. The following tables detail the recorded balance of loans by class that were restructured during three months ended March 31, 2016 by primary type of concession (in thousands):

	Three Months Ended March 31, 2016
	Accruing						Nonaccrual						Total
	Payment Stream		Combination & Other		Total		Payment Stream		Combination & Other		Total
Commercial:
Energy	$	—	$	—	$	—	$	525	$	—	$	525	$	525
Services	—		—		—		—		—		—		—
Wholesale/retail	—		—		—		—		—		—		—
Manufacturing	—		—		—		—		—		—		—
Healthcare	—		—		—		—		—		—		—
Other commercial and industrial	—		—		—		—		—		—		—
Total commercial	—		—		—		525		—		525		525
Commercial real estate:
Residential construction and land development	—		—		—		—		—		—		—
Retail	—		—		—		—		—		—		—
Office	—		—		—		—		—		—		—
Multifamily	—		—		—		—		—		—		—
Industrial	—		—		—		—		—		—		—
Other real estate loans	—		—		—		—		—		—		—
Total commercial real estate	—		—		—		—		—		—		—
Residential mortgage:
Permanent mortgage	—		—		—		367		62		429		429
Permanent mortgage guaranteed by U.S. government agencies	4,331		4,658		8,989		—		90		90		9,079
Home equity	—		—		—		—		622		622		622
Total residential mortgage	4,331		4,658		8,989		367		774		1,141		10,130
Personal	—		—		—		—		10		10		10
Total	$	4,331	$	4,658	$	8,989	$	892	$	784	$	1,676	$	10,665

The following table summarizes, by loan class, the recorded investment at March 31, 2017 and 2016, respectively, of loans modified as TDRs within the previous 12 months and for which there was a payment default during the three months ended March 31, 2017 and 2016, respectively (in thousands):

	Three Months Ended March 31, 2017						Three Months Ended March 31, 2016
	Accruing		Nonaccrual		Total		Accruing		Nonaccrual		Total
Commercial:
Energy	$	—	$	5,646	$	5,646	$	—	$	2,829	$	2,829
Services	—		—		—		—		—		—
Wholesale/retail	—		—		—		—		—		—
Manufacturing	—		—		—		—		—		—
Healthcare	—		—		—		—		—		—
Other commercial and industrial	—		—		—		—		—		—
Total commercial	—		5,646		5,646		—		2,829		2,829
Commercial real estate:
Residential construction and land development	—		—		—		—		—		—
Retail	—		—		—		—		—		—
Office	—		—		—		—		—		—
Multifamily	—		—		—		—		—		—
Industrial	—		—		—		—		—		—
Other real estate loans	—		—		—		—		—		—
Total commercial real estate	—		—		—		—		—		—
Residential mortgage:
Permanent mortgage	—		678		678		—		1,597		1,597
Permanent mortgage guaranteed by U.S. government agencies	17,106		1,136		18,242		22,606		1,346		23,952
Home equity	—		997		997		—		365		365
Total residential mortgage	17,106		2,811		19,917		22,606		3,308		25,914
Personal	—		—		—		—		—		—
Total	$	17,106	$	8,457	$	25,563	$	22,606	$	6,137	$	28,743

A payment default is defined as being 30 days or more past due. The table above includes loans that experienced a payment default during the period, but may be performing in accordance with the modified terms as of the balance sheet date.

Summary of Loans by Aging Status [Table Text Block]

Nonaccrual & Past Due Loans

Past due status for all loan classes is based on the actual number of days since the last payment was due according to the contractual terms of the loans.

A summary of loans currently performing, loans past due and accruing and nonaccrual loans as of March 31, 2017 is as follows (in thousands):

			Past Due
	Current		30 to 59 Days		60 to 89 Days		90 Days or More		Nonaccrual		Total
Commercial:
Energy	$	2,426,100	$	437	$	150	$	—	$	110,425	$	2,537,112
Services	3,002,984		2,395		234		49		7,713		3,013,375
Wholesale/retail	1,495,023		130		—		—		11,090		1,506,243
Manufacturing	537,168		115		240		—		5,907		543,430
Healthcare	2,264,266		—		429		—		909		2,265,604
Other commercial and industrial	440,484		—		81		—		20,781		461,346
Total commercial	10,166,025		3,077		1,134		49		156,825		10,327,110
Commercial real estate:
Residential construction and land development	133,064		314		—		—		2,616		135,994
Retail	744,732		—		—		—		314		745,046
Office	860,476		—		—		—		413		860,889
Multifamily	922,952		15		—		—		24		922,991
Industrial	871,362		25		—		—		76		871,463
Other real estate loans	333,648		—		—		—		1,032		334,680
Total commercial real estate	3,866,234		354		—		—		4,475		3,871,063
Residential mortgage:
Permanent mortgage	948,191		5,364		—		—		24,188		977,743
Permanent mortgages guaranteed by U.S. government agencies	45,643		29,853		—		118,577		10,108		204,181
Home equity	750,914		1,376		266		9		11,785		764,350
Total residential mortgage	1,744,748		36,593		266		118,586		46,081		1,946,274
Personal	846,652		430		105		37		235		847,459
Total	$	16,623,659	$	40,454	$	1,505	$	118,672	$	207,616	$	16,991,906

A summary of loans currently performing, loans past due and accruing and nonaccrual loans as of December 31, 2016 is as follows (in thousands):

			Past Due
	Current		30 to 59 Days		60 to 89 Days	90 Days or More		Nonaccrual		Total
Commercial:
Energy	$	2,364,890	$	479	—	$	—	$	132,499	$	2,497,868
Services	3,099,605		191		1,021	—		8,173		3,108,990
Wholesale/retail	1,561,650		3,761		—	—		11,407		1,576,818
Manufacturing	509,662		382		—	—		4,931		514,975
Healthcare	2,201,050		—		41	—		825		2,201,916
Other commercial and industrial	468,981		155		3	—		21,118		490,257
Total commercial	10,205,838		4,968		1,065	—		178,953		10,390,824
Commercial real estate:
Residential construction and land development	132,100		—		—	—		3,433		135,533
Retail	761,562		—		—	—		326		761,888
Office	798,462		—		—	—		426		798,888
Multifamily	903,234		—		—	—		38		903,272
Industrial	871,673		—		—	—		76		871,749
Other real estate loans	336,488		6		—	—		1,222		337,716
Total commercial real estate	3,803,519		6		—	—		5,521		3,809,046
Residential mortgage:
Permanent mortgage	979,386		3,299		1,280	—		22,855		1,006,820
Permanent mortgages guaranteed by U.S. government agencies	40,594		17,465		13,803	115,679		11,846		199,387
Home equity	729,493		2,276		337	—		11,519		743,625
Total residential mortgage	1,749,473		23,040		15,420	115,679		46,220		1,949,832
Personal	838,811		589		263	5		290		839,958
Total	$	16,597,641	$	28,603	16,748	$	115,684	$	230,984	$	16,989,660

A summary of loans currently performing, loans past due and accruing and nonaccrual loans as of March 31, 2016 is as follows (in thousands):

			Past Due
	Current		30 to 59 Days		60 to 89 Days	90 Days or More		Nonaccrual		Total
Commercial:
Energy	$	2,864,408	$	3,001	—	$	2,458	$	159,553	$	3,029,420
Services	2,714,697		4,682		—	—		9,512		2,728,891
Wholesale/retail	1,443,503		4,658		—	—		3,685		1,451,846
Manufacturing	600,029		—		—	304		312		600,645
Healthcare	1,994,402		—		—	—		1,023		1,995,425
Other commercial and industrial	481,286		266		79	—		567		482,198
Total commercial	10,098,325		12,607		79	2,762		174,652		10,288,425
Commercial real estate:
Residential construction and land development	167,160		—		—	—		4,789		171,949
Retail	809,220		—		—	—		1,302		810,522
Office	694,923		—		—	—		629		695,552
Multifamily	728,183		—		—	5,256		250		733,689
Industrial	564,391		—		—	—		76		564,467
Other real estate loans	392,104		—		—	—		2,224		394,328
Total commercial real estate	3,355,981		—		—	5,256		9,270		3,370,507
Residential mortgage:
Permanent mortgage	918,965		1,378		565	—		27,497		948,405
Permanent mortgages guaranteed by U.S. government agencies	43,259		14,835		12,490	107,216		19,550		197,350
Home equity	710,824		1,945		255	—		10,530		723,554
Total residential mortgage	1,673,048		18,158		13,310	107,216		57,577		1,869,309
Personal	493,722		266		5	1		331		494,325
Total	$	15,621,076	$	31,031	13,394	$	115,235	$	241,830	$	16,022,566