CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (unaudited) - USD ($) $ in Thousands		Total	Fixed-Rate Reset Non-Cumulative Perpetual Preferred Stock, Series E	FCB Financial Holdings, Inc.	Impact from Adoption		Preferred Stock	Preferred Stock Fixed-Rate Reset Non-Cumulative Perpetual Preferred Stock, Series E	Common Stock	Common Stock FCB Financial Holdings, Inc.	Additional Paid-in Capital	Additional Paid-in Capital FCB Financial Holdings, Inc.	Treasury Stock	Treasury Stock FCB Financial Holdings, Inc.	Accumulated Other Comprehensive Income (Loss)	Retained Earnings	Retained Earnings FCB Financial Holdings, Inc.	Retained Earnings Impact from Adoption
Accounting Standards Update [Extensible List]		us-gaap:AccountingStandardsUpdate201602Member
Balance at Dec. 31, 2018		$ 3,133,602			$ 4,270		$ 195,140		$ 143,300		$ 3,060,561		$ (1,014,746)		$ (94,420)	$ 843,767		$ 4,270
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		412,096														412,096
Other comprehensive income (loss), net of income taxes		170,353													170,353
Issuance of common stock, net of issuance costs				$ 704,146						$ 22,043		$ 682,103
Common stock issued				877,570										$ 1,014,746			$ (137,176)
Fair value of exchanged equity awards and warrants attributed to purchase price				$ 43,972								$ 43,972
Cash dividends declared on common stock		(138,947)														(138,947)
Cash dividends declared on preferred stock	[1]	(14,591)														(14,591)
Stock Issued During Period, Value, New Issues			$ 341,410					$ 341,410
Repurchases of stock including costs to repurchase		(688,860)											(688,860)
Restricted share unit vesting and taxes paid related to net share settlement		(8,741)							294		(8,709)					(326)
Stock options/warrants exercised, net		11,162							564		10,598		0
Warrants exercised with net settlement and common stock reissued		0									(8,763)		8,779			(16)
Share-based compensation expense		21,396									21,396
Balance at Sep. 30, 2019		4,868,838					536,550		166,201		3,801,158		(680,081)		75,933	969,077
Balance at Jun. 30, 2019		4,753,816					195,140		166,080		3,801,748		(344,901)		49,289	886,460
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		135,726														135,726
Other comprehensive income (loss), net of income taxes		26,644													26,644
Cash dividends declared on common stock		(44,476)														(44,476)
Cash dividends declared on preferred stock	[2]	(8,291)														(8,291)
Stock Issued During Period, Value, New Issues			$ 341,410					$ 341,410
Repurchases of stock including costs to repurchase		(343,690)											(343,690)
Restricted share unit vesting and taxes paid related to net share settlement		(98)							9		219					(326)
Stock options/warrants exercised, net		2,626							112		2,514
Warrants exercised with net settlement and common stock reissued		0									(8,494)		8,510			(16)
Share-based compensation expense		5,171									5,171
Balance at Sep. 30, 2019		$ 4,868,838					536,550		166,201		3,801,158		(680,081)		75,933	969,077
Accounting Standards Update [Extensible List]		us-gaap:AccountingStandardsUpdate201613Member
Balance at Dec. 31, 2019		$ 4,941,690			(35,721)	[3]	537,145		166,801		3,819,336		(715,560)		65,641	1,068,327		(35,721)	[3]
Accounting Standards Update [Extensible List]		us-gaap:AccountingStandardsUpdate201613Member
Balance at Dec. 31, 2019		$ 4,941,690			$ (35,721)	[3]	537,145		166,801		3,819,336		(715,560)		65,641	1,068,327		$ (35,721)	[3]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		223,286														223,286
Other comprehensive income (loss), net of income taxes		109,273													109,273
Cash dividends declared on common stock		(145,824)														(145,824)
Cash dividends declared on preferred stock	[1]	(24,872)														(24,872)
Repurchases of stock including costs to repurchase		(16,246)											(16,246)
Restricted share unit vesting and taxes paid related to net share settlement		(7,428)							381		(7,349)					(460)
Stock options/warrants exercised, net		6,511							229		6,282
Share-based compensation expense		13,873									13,873
Balance at Sep. 30, 2020		5,064,542					537,145		167,411		3,832,142		(731,806)		174,914	1,084,736
Balance at Jun. 30, 2020		5,052,968					537,145		167,406		3,826,726		(731,806)		202,970	1,050,527
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		91,574														91,574
Other comprehensive income (loss), net of income taxes		(28,056)													(28,056)
Cash dividends declared on common stock		(48,614)														(48,614)
Cash dividends declared on preferred stock	[2]	(8,291)														(8,291)
Restricted share unit vesting and taxes paid related to net share settlement		(24)							2		434					(460)
Stock options/warrants exercised, net		33							3		30
Share-based compensation expense		4,952									4,952
Balance at Sep. 30, 2020		$ 5,064,542					$ 537,145		$ 167,411		$ 3,832,142		$ (731,806)		$ 174,914	$ 1,084,736

[1] For the nine months ended September 30, 2020, dividends per share were $1.17 and $1.11 for Series D and Series E Preferred Stock, respectively. For the nine months ended September 30, 2019, dividends per share were $1.17 and $0.37 for Series D and Series E Preferred Stock, respectively.

[2] For the three months ended September 30, 2020, dividends per share were $0.39 and $0.37 for Series D and Series E Preferred Stock, respectively. For the three months ended September 30, 2019, dividends per share were $0.39 and $0.37 for Series D and Series E Preferred Stock, respectively.

[3] For additional information, see "Part I - Item 1. Financial Statements and Supplementary Data - Note 1 - Basis of Presentation" in this Report.