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Capital Conservation Buffer

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Capital Conservation Buffer, Annual Percentage Increase

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Capital required for common equity Tier 1 capital to risk-weighted assets

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Common equity Tier 1 required to be well capitalized to risk-weighted assets

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Fully Phased In 2019 Capital Conservation Buffer

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Maximum Undivided Profits Elgible For Dividend Payment Without Changing Well Capitalized Status

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Subordinated Debt, Annual Tier 2 Discount Percentage

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The number of votes allowed for common stock dividends

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The amount of total capital as defined in the regulations.

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The minimum Total risk based capital ratio (total capital divided by risk weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action.

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The Total risk based capital ratio (total capital divided by risk weighted assets) required to be categorized as "well capitalized", in the regulatory framework for prompt corrective action.

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Total Capital divided by risk weighted assets as defined in the regulations.

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Amount of Common Equity Tier One Risk-based Capital, as defined by regulatory framework.

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Percentage of Common Equity Tier One Risk-based Capital to total risk-weighted assets, as defined by regulatory framework.

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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 operating dividend income on securities.

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The number of shares authorized to be repurchased by an entity's Board of Directors under a stock repurchase plan.

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Number of shares that have been repurchased and retired during the period.

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Number of shares that have been repurchased during the period and have not been retired and are not held in treasury. Some state laws may govern the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

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Tier 1 Leverage Capital as defined in the regulations. Also called Core Capital.

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The minimum amount of Tier 1 Leverage Capital for capital adequacy purposes divided by average assets as defined in the regulations.

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The amount of Tier 1 Leverage Capital required to be categorized as well capitalized divided by average assets as defined in the regulatory framework for prompt corrective action.

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Tier 1 Leverage Capital divided by average assets as defined in the regulations.

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Tier 1 Risk Based Capital as defined in the regulations.

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The minimum Tier One Capital Ratio (Tier one capital divided by risk-weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action.

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The Tier 1 capital ratio (Tier 1 capital divided by risk weighted assets) required to be categorized as "well capitalized" under the regulatory framework for prompt corrective action.

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Tier 1 capital divided by risk weighted assets as defined by regulations.

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Tier 2 risk-based capital as defined in the regulations.

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Shareholders' Equity, Dividends Restrictions and Other Regulatory Matters (Details) $ in Thousands	2 Months Ended		10 Months Ended	12 Months Ended
	Feb. 20, 2019 shares	Dec. 31, 2018 USD ($) Rate shares	Oct. 31, 2018 shares	Dec. 31, 2018 USD ($) vote Rate shares	Dec. 31, 2017 USD ($) Rate shares	Dec. 31, 2016 USD ($)	Nov. 01, 2018 shares
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Capital required for common equity Tier 1 capital to risk-weighted assets		4.50%		4.50%
Dividends from subsidiaries				$ 242,910
Tier 1 Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets		6.00%		6.00%
Capital Required for Capital Adequacy to Risk Weighted Assets		8.00%		8.00%
Leverage Capital Required Ratio To Tangible Assets		4.00%		4.00%
Tier 2 capital		$ 20,000		$ 20,000	$ 0
Subordinated Debt, Annual Tier 2 Discount Percentage \| Rate		0.00%		0.00%	20.00%
Maximum Undivided Profits Elgible For Dividend Payment Without Changing Well Capitalized Status		$ 1,092,100		$ 1,092,100
Average Required Maintence Of Non Interst Bearing Reserve Balance				$ 680,300
Capital Conservation Buffer, Annual Percentage Increase		0.625%		0.625%
Capital Conservation Buffer		1.88%		1.88%	0.625%
Fully Phased In 2019 Capital Conservation Buffer		2.50%		2.50%
Common Class A [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Votes per share of common stock \| vote				1
Stock Repurchase Program, Number of Shares Authorized to be Repurchased \| shares		800,000		800,000			800,000
Stock Repurchased During Period, Shares \| shares				382,000	0
Stock Repurchased and Retired During Period, Shares \| shares		182,000	200,000
Common Class A [Member] \| Subsequent Event
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Stock Repurchased and Retired During Period, Shares \| shares	106,500
Class B Common Stock
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Votes per share of common stock \| vote				16
Stock Repurchased and Retired During Period, Shares \| shares				0	0
Parent
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Dividends from subsidiaries					$ 50,424	$ 90,100
BancShares [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier 1 Capital for Capital Adequacy		$ 3,463,307		$ 3,463,307	3,287,364
Capital Required for Capital Adequacy		3,826,626		3,826,626	3,626,789
Leverage Capital Required for Capital Adequacy		$ 3,463,307		$ 3,463,307	$ 3,287,364
Tier 1 Risk Based Capital to Risk Weighted Assets		12.67%		12.67%	12.88%
Capital to Risk Weighted Assets		13.99%		13.99%	14.21%
Leverage Capital to Average Assets		9.77%		9.77%	9.47%
Tier 1 Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets		8.00%		8.00%	8.00%
Common equity Tier 1		$ 3,463,307		$ 3,463,307	$ 3,287,364
Common equity Tier 1 to risk-weighted assets		12.67%		12.67%	12.88%
Common equity Tier 1 required to be well capitalized to risk-weighted assets		6.50%		6.50%	6.50%
Capital Required to be Well Capitalized		10.00%		10.00%	10.00%
Leverage Capital Required to be Well Capitalized to Average Assets		5.00%		5.00%	5.00%
Capital Conservation Buffer		5.99%		5.99%
FCB [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier 1 Capital for Capital Adequacy		$ 3,315,742		$ 3,315,742	$ 3,189,709
Capital Required for Capital Adequacy		3,574,561		3,574,561	3,422,634
Leverage Capital Required for Capital Adequacy		$ 3,315,742		$ 3,315,742	$ 3,189,709
Tier 1 Risk Based Capital to Risk Weighted Assets		12.17%		12.17%	12.54%
Capital to Risk Weighted Assets		13.12%		13.12%	13.46%
Leverage Capital to Average Assets		9.39%		9.39%	9.22%
Tier 1 Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets		8.00%		8.00%	8.00%
Common equity Tier 1		$ 3,315,742		$ 3,315,742	$ 3,189,709
Common equity Tier 1 to risk-weighted assets		12.17%		12.17%	12.54%
Common equity Tier 1 required to be well capitalized to risk-weighted assets		6.50%		6.50%	6.50%
Capital Required to be Well Capitalized		10.00%		10.00%	10.00%
Leverage Capital Required to be Well Capitalized to Average Assets		5.00%		5.00%	5.00%
Capital Conservation Buffer		5.12%		5.12%