Loans and Allowance for Loan Losses (Schedule of Current, Accruing Past Due and Nonaccrual Loans) (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019	Jan. 01, 2019
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	$ 39,914,297	$ 37,162,450
Non-accrual	120,956	99,848
Non-accrual, without an allowance	26,481
Total loans	40,012,482	37,187,814
Deferred fees and costs, net	98,200	25,400
FCB Financial Holdings, Inc.
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
ASC 310-30 Loans		5,557,334
Loans	90,300		$ 9,290,000
Acquired Loans, ASC 310-30 | FCB Financial Holdings, Inc.
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Non-accrual	1,800
Total commercial and industrial
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Non-accrual	76,741	65,797
Non-accrual, without an allowance	25,864
Total loans	19,938,276	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		1,842,331
Total commercial and industrial | Commercial, financial and agricultural
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Non-accrual	67,535	56,017
Non-accrual, without an allowance	15,465
Total loans	13,136,696	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		1,019,135
Total commercial and industrial | Owner-occupied
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Non-accrual	9,206	9,780
Non-accrual, without an allowance	10,399
Total loans	6,801,580	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		823,196
Total commercial real estate
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Non-accrual	8,377	4,944
Non-accrual, without an allowance	265
Total loans	10,827,535	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		1,856,170
Total commercial real estate | Investment properties
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Non-accrual	1,638	1,581
Non-accrual, without an allowance	0
Total loans	9,447,200	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		1,736,608
Total commercial real estate | 1-4 family properties
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Non-accrual	4,437	2,253
Non-accrual, without an allowance	0
Total loans	696,808	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		41,401
Total commercial real estate | Land and development
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Non-accrual	2,302	1,110
Non-accrual, without an allowance	265
Total loans	683,527	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		78,161
Total consumer
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Non-accrual	35,838	29,107
Non-accrual, without an allowance	352
Total loans	9,246,671	9,924,660
Total consumer | FCB Financial Holdings, Inc.
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
ASC 310-30 Loans		1,858,833
Total consumer | Consumer mortgages
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Non-accrual	17,086	11,369
Non-accrual, without an allowance	352
Total loans	5,811,376	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		1,848,493
Total consumer | Home equity lines
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Non-accrual	14,200	12,034
Non-accrual, without an allowance	0
Total loans	1,710,264	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		2,155
Total consumer | Credit cards
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Non-accrual	0	0
Non-accrual, without an allowance	0
Total loans	250,448	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		0
Total consumer | Other consumer loans
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Non-accrual	4,552	5,704
Non-accrual, without an allowance	0
Total loans	1,474,583	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		8,185
Current
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	39,818,655	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	19,820,626	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	13,041,583	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	6,779,043	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	10,814,720	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	9,444,615	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	689,660	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	680,445	629,363
Current | Total consumer
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	9,183,309	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	5,786,762	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	1,692,542	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	243,333	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	1,460,672	2,363,101
Accruing 30 to 89 Days Past Due
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	37,999	81,330
Accruing 30 to 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	26,500
Accruing 30 to 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	11,409	44,080
Accruing 30 to 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	9,515	38,916
Accruing 30 to 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	1,894	5,164
Accruing 30 to 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	2,805	4,225
Accruing 30 to 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	829	1,344
Accruing 30 to 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	1,507	2,073
Accruing 30 to 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	469	808
Accruing 30 to 89 Days Past Due | Total consumer
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	23,785	33,025
Accruing 30 to 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	7,176	4,223
Accruing 30 to 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	3,495	7,038
Accruing 30 to 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	4,395	3,076
Accruing 30 to 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	8,719	18,688
Accruing 90 to 149 Days Past Due
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	8,391	6,303
Accruing 90 to 149 Days Past Due | Acquired Loans, ASC 310-30 | FCB Financial Holdings, Inc.
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans	9,600
Accruing 90 to 149 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	3,636	1,782
Accruing 90 to 149 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	2,598	1,206
Accruing 90 to 149 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	1,038	576
Accruing 90 to 149 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	1,368	304
Accruing 90 to 149 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	118	0
Accruing 90 to 149 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	1,204	304
Accruing 90 to 149 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	46	0
Accruing 90 to 149 Days Past Due | Total consumer
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	3,387	4,217
Accruing 90 to 149 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	0	730
Accruing 90 to 149 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	27	171
Accruing 90 to 149 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	2,720	2,700
Accruing 90 to 149 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	640	616
Total Accruing Past Due
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Loans, net of deferred fees and costs	46,390	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	15,045	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	12,113	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	2,932	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	4,173	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	947	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	2,711	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	515	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	27,172	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	7,176	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	3,522	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	7,115	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	$ 9,359	$ 19,304