Loans And Allowance For Loan Losses (Schedule Of Current, Accruing Past Due And Nonaccrual Loans) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	$ 38,252,984	$ 37,162,450
Non-accrual with an ALL	127,720	99,848
Non-accrual without an ALL	23,359
Financing Receivable, before Allowance for Credit Loss and Fee	38,330,656	37,187,814
Deferred fees and costs, net	(77,700)	(25,400)
Loans and Leases Receivable, Impaired, Interest Income Recognized, Change in Present Value Attributable to Passage of Time	$ 3,900	$ 3,300
Allowance for loan and lease losses, percent of loan amount	50.00%	50.00%
FCB Financial Holdings, Inc.
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
ASC 310-30 Loans(2)		$ 5,557,334
Loans, net of deferred fees and costs	$ 90,300
Acquired Loans, ASC 310-30 | FCB Financial Holdings, Inc.
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Non-accrual with an ALL	1,800
Payment Protection Program Loans
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Deferred fees and costs, net	48,900
Total commercial and industrial
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Non-accrual with an ALL	75,546	65,797
Non-accrual without an ALL	21,859
Financing Receivable, before Allowance for Credit Loss and Fee	19,373,679	16,769,370
Total commercial and industrial | FCB Financial Holdings, Inc.
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
ASC 310-30 Loans(2)		1,842,331
Total commercial and industrial | Commercial, financial, and agricultural
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Non-accrual with an ALL	55,527	56,017
Non-accrual without an ALL	21,859
Financing Receivable, before Allowance for Credit Loss and Fee	12,574,899	10,239,559
Total commercial and industrial | Commercial, financial, and agricultural | FCB Financial Holdings, Inc.
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
ASC 310-30 Loans(2)		1,019,135
Total commercial and industrial | Owner-occupied
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Non-accrual with an ALL	20,019	9,780
Non-accrual without an ALL	0
Financing Receivable, before Allowance for Credit Loss and Fee	6,798,780	6,529,811
Total commercial and industrial | Owner-occupied | FCB Financial Holdings, Inc.
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
ASC 310-30 Loans(2)		823,196
Total commercial real estate
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Non-accrual with an ALL	28,913	4,944
Non-accrual without an ALL	1,500
Financing Receivable, before Allowance for Credit Loss and Fee	10,570,434	10,493,784
Total commercial real estate | FCB Financial Holdings, Inc.
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
ASC 310-30 Loans(2)		1,856,170
Total commercial real estate | Investment properties
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Non-accrual with an ALL	24,631	1,581
Non-accrual without an ALL	0
Financing Receivable, before Allowance for Credit Loss and Fee	9,346,530	9,004,327
Total commercial real estate | Investment properties | FCB Financial Holdings, Inc.
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
ASC 310-30 Loans(2)		1,736,608
Total commercial real estate | 1-4 family properties
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Non-accrual with an ALL	2,383	2,253
Non-accrual without an ALL	1,236
Financing Receivable, before Allowance for Credit Loss and Fee	629,168	780,015
Total commercial real estate | 1-4 family properties | FCB Financial Holdings, Inc.
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
ASC 310-30 Loans(2)		41,401
Total commercial real estate | Land and development
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Non-accrual with an ALL	1,899	1,110
Non-accrual without an ALL	264
Financing Receivable, before Allowance for Credit Loss and Fee	594,736	709,442
Total commercial real estate | Land and development | FCB Financial Holdings, Inc.
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
ASC 310-30 Loans(2)		78,161
Total consumer
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Non-accrual with an ALL	23,261	29,107
Non-accrual without an ALL	0
Financing Receivable, before Allowance for Credit Loss and Fee	8,386,543	9,924,660
Total consumer | FCB Financial Holdings, Inc.
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
ASC 310-30 Loans(2)		1,858,833
Total consumer | Consumer mortgages
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Non-accrual with an ALL	8,740	11,369
Non-accrual without an ALL	0
Financing Receivable, before Allowance for Credit Loss and Fee	5,507,700	5,546,368
Total consumer | Consumer mortgages | FCB Financial Holdings, Inc.
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
ASC 310-30 Loans(2)		1,848,493
Total consumer | Home equity lines
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Non-accrual with an ALL	12,145	12,034
Non-accrual without an ALL	0
Financing Receivable, before Allowance for Credit Loss and Fee	1,523,836	1,713,157
Total consumer | Home equity lines | FCB Financial Holdings, Inc.
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
ASC 310-30 Loans(2)		2,155
Total consumer | Credit cards
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Non-accrual with an ALL	0	0
Non-accrual without an ALL	0
Financing Receivable, before Allowance for Credit Loss and Fee	281,018	268,841
Total consumer | Credit cards | FCB Financial Holdings, Inc.
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
ASC 310-30 Loans(2)		0
Total consumer | Other consumer loans
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Non-accrual with an ALL	2,376	5,704
Non-accrual without an ALL	0
Financing Receivable, before Allowance for Credit Loss and Fee	1,073,989	2,396,294
Total consumer | Other consumer loans | FCB Financial Holdings, Inc.
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
ASC 310-30 Loans(2)		8,185
Current
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	38,132,228	31,442,999
Current | Total commercial and industrial
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	19,263,017	14,815,380
Current | Total commercial and industrial | Commercial, financial, and agricultural
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	12,486,261	9,124,285
Current | Total commercial and industrial | Owner-occupied
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	6,776,756	5,691,095
Current | Total commercial real estate
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	10,533,110	8,628,141
Current | Total commercial real estate | Investment properties
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	9,318,994	7,264,794
Current | Total commercial real estate | 1-4 family properties
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	621,965	733,984
Current | Total commercial real estate | Land and development
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	592,151	629,363
Current | Total consumer
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	8,336,101	7,999,478
Current | Total consumer | Consumer mortgages
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	5,489,624	3,681,553
Current | Total consumer | Home equity lines
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	1,507,685	1,691,759
Current | Total consumer | Credit cards
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	276,778	263,065
Current | Total consumer | Other consumer loans
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	1,062,014	2,363,101
Accruing 30-89 Days Past Due
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	43,232	81,330
Accruing 30-89 Days Past Due | Acquired Loans, ASC 310-30 | FCB Financial Holdings, Inc.
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	26,500
Accruing 30-89 Days Past Due | Total commercial and industrial
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	12,169	44,080
Accruing 30-89 Days Past Due | Total commercial and industrial | Commercial, financial, and agricultural
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	10,256	38,916
Accruing 30-89 Days Past Due | Total commercial and industrial | Owner-occupied
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	1,913	5,164
Accruing 30-89 Days Past Due | Total commercial real estate
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	6,721	4,225
Accruing 30-89 Days Past Due | Total commercial real estate | Investment properties
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	2,751	1,344
Accruing 30-89 Days Past Due | Total commercial real estate | 1-4 family properties
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	3,548	2,073
Accruing 30-89 Days Past Due | Total commercial real estate | Land and development
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	422	808
Accruing 30-89 Days Past Due | Total consumer
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	24,342	33,025
Accruing 30-89 Days Past Due | Total consumer | Consumer mortgages
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	8,851	4,223
Accruing 30-89 Days Past Due | Total consumer | Home equity lines
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	4,006	7,038
Accruing 30-89 Days Past Due | Total consumer | Credit cards
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	2,363	3,076
Accruing 30-89 Days Past Due | Total consumer | Other consumer loans
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	9,122	18,688
Accruing 90 Days or Greater Past Due
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	4,117	6,303
Accruing 90 Days or Greater Past Due | Acquired Loans, ASC 310-30 | FCB Financial Holdings, Inc.
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	9,600
Accruing 90 Days or Greater Past Due | Total commercial and industrial
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	1,088	1,782
Accruing 90 Days or Greater Past Due | Total commercial and industrial | Commercial, financial, and agricultural
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	996	1,206
Accruing 90 Days or Greater Past Due | Total commercial and industrial | Owner-occupied
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	92	576
Accruing 90 Days or Greater Past Due | Total commercial real estate
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	190	304
Accruing 90 Days or Greater Past Due | Total commercial real estate | Investment properties
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	154	0
Accruing 90 Days or Greater Past Due | Total commercial real estate | 1-4 family properties
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	36	304
Accruing 90 Days or Greater Past Due | Total commercial real estate | Land and development
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	0	0
Accruing 90 Days or Greater Past Due | Total consumer
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	2,839	4,217
Accruing 90 Days or Greater Past Due | Total consumer | Consumer mortgages
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	485	730
Accruing 90 Days or Greater Past Due | Total consumer | Home equity lines
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	0	171
Accruing 90 Days or Greater Past Due | Total consumer | Credit cards
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	1,877	2,700
Accruing 90 Days or Greater Past Due | Total consumer | Other consumer loans
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	477	616
Total Accruing Past Due
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	47,349	87,633
Total Accruing Past Due | Total commercial and industrial
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	13,257	45,862
Total Accruing Past Due | Total commercial and industrial | Commercial, financial, and agricultural
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	11,252	40,122
Total Accruing Past Due | Total commercial and industrial | Owner-occupied
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	2,005	5,740
Total Accruing Past Due | Total commercial real estate
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	6,911	4,529
Total Accruing Past Due | Total commercial real estate | Investment properties
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	2,905	1,344
Total Accruing Past Due | Total commercial real estate | 1-4 family properties
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	3,584	2,377
Total Accruing Past Due | Total commercial real estate | Land and development
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	422	808
Total Accruing Past Due | Total consumer
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	27,181	37,242
Total Accruing Past Due | Total consumer | Consumer mortgages
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	9,336	4,953
Total Accruing Past Due | Total consumer | Home equity lines
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	4,006	7,209
Total Accruing Past Due | Total consumer | Credit cards
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	4,240	5,776
Total Accruing Past Due | Total consumer | Other consumer loans
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	$ 9,599	$ 19,304