Allowance for Loan and Lease Losses (Allocation of Allowance for Loan and Lease Losses) (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Modifications, Recorded Investment	$ 153,517		$ 156,130
Unpaid principal balance	810,683	$ 1,108,379
Loans and Leases Receivable, Net Amount	25,235,010		25,299,564
Non-PCI impaired loans less than $500,000 collectively evaluated	44,800		47,100
Commercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Modifications, Recorded Investment	71,021		74,560
Commercial \| Construction and land development
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Modifications, Recorded Investment	2,243		2,298
Commercial \| Mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Modifications, Recorded Investment	57,855		61,065
Commercial \| Other commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Modifications, Recorded Investment	541		860
Commercial \| Commercial and industrial
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Modifications, Recorded Investment	10,045		10,046
Commercial \| Other
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Modifications, Recorded Investment	337		291
Noncommercial
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Modifications, Recorded Investment	82,496		81,570
Noncommercial \| Construction and land development
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Modifications, Recorded Investment	2,330		2,337
Noncommercial \| Consumer and Other
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Modifications, Recorded Investment	2,953		3,021
Noncommercial \| Mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Modifications, Recorded Investment	47,693		47,524
Noncommercial \| Revolving mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Modifications, Recorded Investment	29,520		28,688
PCI Loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Modifications, Recorded Investment	17,921		18,220
Acquired loans which have adverse change in expected cash flows	160,400		186,600
Provision for Loan, Lease, and Other Losses	(164)	2,354
Financing Receivable, Allowance for Credit Losses, Write-downs	0	(84)
Recoveries	0	0
Non-PCI Loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	167,080		163,902
ALLL for loans and leases individually evaluated for impairment	11,965		9,827
Impaired Financing Receivable, with Related Allowance, Recorded Investment	122,376		115,073
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	27,625		31,357
Financing Receivable, Individually Evaluated for Impairment	150,001		146,430
Average balance	147,891	155,025
Interest income recognized	1,339	1,372
Provision for Loan, Lease, and Other Losses	11,914	5,251
Financing Receivable, Allowance for Credit Losses, Write-downs	(10,154)	(9,613)
Recoveries	3,467	3,315
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	207,830		204,741
Financing Receivable, Collectively Evaluated for Impairment	24,756,428		24,770,270
Loans and Leases Receivable, Net Amount	24,906,429		24,916,700
Non-PCI Loans \| Commercial \| Construction and land development
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	2,538		2,606
ALLL for loans and leases individually evaluated for impairment	533		490
Impaired Financing Receivable, with Related Allowance, Recorded Investment	1,932		1,897
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	191		278
Financing Receivable, Individually Evaluated for Impairment	2,123		2,175
Average balance	2,147	1,155
Interest income recognized	28	11
Provision for Loan, Lease, and Other Losses	2,119	2,225
Financing Receivable, Allowance for Credit Losses, Write-downs	(44)	0
Recoveries	131	23
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	36,943		34,780
Financing Receivable, Collectively Evaluated for Impairment	802,340		755,679
Loans and Leases Receivable, Net Amount	804,463		757,854
Non-PCI Loans \| Commercial \| Mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	61,845		61,317
ALLL for loans and leases individually evaluated for impairment	2,949		2,671
Impaired Financing Receivable, with Related Allowance, Recorded Investment	37,575		34,177
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	18,582		21,270
Financing Receivable, Individually Evaluated for Impairment	56,157		55,447
Average balance	56,629	72,267
Interest income recognized	564	711
Provision for Loan, Lease, and Other Losses	2,371	(1,365)
Financing Receivable, Allowance for Credit Losses, Write-downs	(761)	(46)
Recoveries	220	239
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	42,332		40,780
Financing Receivable, Collectively Evaluated for Impairment	10,691,558		10,661,787
Loans and Leases Receivable, Net Amount	10,747,715		10,717,234
Non-PCI Loans \| Commercial \| Other commercial real estate
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	629		946
ALLL for loans and leases individually evaluated for impairment	16		42
Impaired Financing Receivable, with Related Allowance, Recorded Investment	222		243
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	319		617
Financing Receivable, Individually Evaluated for Impairment	541		860
Average balance	685	1,713
Interest income recognized	8	11
Provision for Loan, Lease, and Other Losses	(83)	(1,293)
Financing Receivable, Allowance for Credit Losses, Write-downs	0	0
Recoveries	1	145
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	2,383		2,439
Financing Receivable, Collectively Evaluated for Impairment	426,878		426,125
Loans and Leases Receivable, Net Amount	427,419		426,985
Non-PCI Loans \| Commercial \| Commercial and industrial
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	14,002		14,695
ALLL for loans and leases individually evaluated for impairment	1,420		1,137
Impaired Financing Receivable, with Related Allowance, Recorded Investment	7,613		7,153
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	2,374		2,715
Financing Receivable, Individually Evaluated for Impairment	9,987		9,868
Average balance	10,000	9,762
Interest income recognized	100	87
Provision for Loan, Lease, and Other Losses	2,725	562
Financing Receivable, Allowance for Credit Losses, Write-downs	(1,858)	(2,329)
Recoveries	538	1,260
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	55,605		54,483
Financing Receivable, Collectively Evaluated for Impairment	3,869,588		3,928,862
Loans and Leases Receivable, Net Amount	3,879,575		3,938,730
Non-PCI Loans \| Commercial \| Other
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	353		301
ALLL for loans and leases individually evaluated for impairment	151		105
Impaired Financing Receivable, with Related Allowance, Recorded Investment	262		216
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	75		75
Financing Receivable, Individually Evaluated for Impairment	337		291
Average balance	315	0
Interest income recognized	2	0
Provision for Loan, Lease, and Other Losses	(498)	114
Financing Receivable, Allowance for Credit Losses, Write-downs	0	(3)
Recoveries	444	42
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	2,016		2,116
Financing Receivable, Collectively Evaluated for Impairment	280,511		296,133
Loans and Leases Receivable, Net Amount	280,848		296,424
Non-PCI Loans \| Noncommercial \| Construction and land development
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	4,045		4,035
ALLL for loans and leases individually evaluated for impairment	99		81
Impaired Financing Receivable, with Related Allowance, Recorded Investment	2,330		2,337
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	1,412		1,412
Financing Receivable, Individually Evaluated for Impairment	3,742		3,749
Average balance	3,747	4,104
Interest income recognized	36	48
Provision for Loan, Lease, and Other Losses	123	107
Financing Receivable, Allowance for Credit Losses, Write-downs	0	(182)
Recoveries	0	26
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	2,374		2,269
Financing Receivable, Collectively Evaluated for Impairment	255,217		253,281
Loans and Leases Receivable, Net Amount	258,959		257,030
Non-PCI Loans \| Noncommercial \| Mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	48,216		45,226
ALLL for loans and leases individually evaluated for impairment	3,149		1,901
Impaired Financing Receivable, with Related Allowance, Recorded Investment	43,553		40,359
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	1,391		1,809
Financing Receivable, Individually Evaluated for Impairment	44,944		42,168
Average balance	42,626	38,724
Interest income recognized	325	275
Provision for Loan, Lease, and Other Losses	1,508	1,512
Financing Receivable, Allowance for Credit Losses, Write-downs	(166)	(806)
Recoveries	173	77
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	13,838		13,571
Financing Receivable, Collectively Evaluated for Impairment	4,258,193		4,223,519
Loans and Leases Receivable, Net Amount	4,303,137		4,265,687
Non-PCI Loans \| Noncommercial \| Revolving mortgage
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	32,074		31,371
ALLL for loans and leases individually evaluated for impairment	2,742		2,515
Impaired Financing Receivable, with Related Allowance, Recorded Investment	26,017		25,751
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	3,199		3,101
Financing Receivable, Individually Evaluated for Impairment	29,216		28,852
Average balance	28,742	24,792
Interest income recognized	247	201
Provision for Loan, Lease, and Other Losses	209	466
Financing Receivable, Allowance for Credit Losses, Write-downs	(963)	(992)
Recoveries	387	194
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	18,753		19,347
Financing Receivable, Collectively Evaluated for Impairment	2,440,682		2,514,123
Loans and Leases Receivable, Net Amount	2,469,898		2,542,975
Non-PCI Loans \| Noncommercial \| Consumer
Financing Receivable, Allowance for Credit Losses [Line Items]
Unpaid principal balance	3,378		3,405
ALLL for loans and leases individually evaluated for impairment	906		885
Impaired Financing Receivable, with Related Allowance, Recorded Investment	2,872		2,940
Impaired Financing Receivable, with No Related Allowance, Recorded Investment	82		80
Financing Receivable, Individually Evaluated for Impairment	2,954		3,020
Average balance	3,000	2,508
Interest income recognized	29	28
Provision for Loan, Lease, and Other Losses	3,440	2,923
Financing Receivable, Allowance for Credit Losses, Write-downs	(6,362)	(5,255)
Recoveries	1,573	$ 1,309
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	33,586		34,956
Financing Receivable, Collectively Evaluated for Impairment	1,731,461		1,710,761
Loans and Leases Receivable, Net Amount	$ 1,734,415		$ 1,713,781

Acquired Loans Which Have Adverse Change In Expected Cash Flows

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- Definition

The recorded investment of impaired financing receivables less than $500,000 that are collectively evaluated.

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The valuation allowance for financing receivables that are expected to be uncollectible that were collectively evaluated for impairment.

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Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount of recovery of financing receivables doubtful of collection that were previously charged off.

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Amount of direct write-downs of financing receivables charged against the allowance.

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The balance of financing receivables that were collectively evaluated for impairment.

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- Definition

The amount of the outstanding recorded investment related to financing receivables that have been modified by troubled debt restructurings.

+ References

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Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

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- Definition

Amount of interest income recognized that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were impaired.

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Amount of unpaid principal balance of impaired financing receivables with related allowance for credit losses and without related allowance for credit losses.

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Amount of investment in impaired financing receivables for which there is no related allowance for credit losses.

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Amount of investment in impaired financing receivables for which there is a related allowance for credit losses.

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Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements and loans held for sale.

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Amount of expense related loan transactions, lease transactions, credit loss from transactions other than loan and lease transactions, and other loss based on assessment of uncollectability from the counterparty to reduce the account to their net realizable value.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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