Regulatory Capital Requirements and Dividends From Subsidiaries - Narrative (Details) $ / shares in Units, shares in Thousands, $ in Thousands			12 Months Ended
	Mar. 26, 2020 USD ($)	Mar. 12, 2020 USD ($) $ / shares shares	Dec. 31, 2021 USD ($) vote $ / shares	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Trust Preferred Securities			$ 128,100	$ 128,500
Net proceeds from preferred stock issuance			0	339,937	$ 0
Dividends from subsidiaries			$ 173,091	229,700	$ 149,800
Average Required Maintence Of Non Interst Bearing Reserve Balance	$ 75,000
Non-Cumulative Perpetual Preferred Stock, Series A [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Preferred Stock, dividend rate, percentage		5.375%
Preferred stock, par value (in dollars per share) | $ / shares		$ 0.01
Fixed-to-Floating Rate Subordinated Notes Due 2030 [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Preferred stock, Liquidation Preference Per Share | $ / shares		$ 25	$ 25
Qualifying Subordinated Debentures [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier 2 capital			$ 350,000	$ 377,500
Common Class A [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Votes per share of common stock | vote			1
Class B Common Stock
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Votes per share of common stock | vote			16
Depositary Shares, Each Representing a 1/40th Interest in a Share of 5.375% Non-Cumulative Perpetual Preferred Stock, Series A
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Stock Issued During Period, Shares, New Issues | shares		13,800
Net proceeds from preferred stock issuance		$ 345,000
BancShares
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Capital Conservation Buffer				6.35%
FCB
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Capital Conservation Buffer				5.85%
Maintain Well-capitalized Banks, Additional Dividends Can Be Paid			$ 1,350,000