Mergers and Acquisitions - Atlantic Capital (Details) $ / shares in Units, $ in Thousands		3 Months Ended
	Mar. 01, 2022 USD ($) $ / shares shares	Mar. 31, 2022 USD ($)	Mar. 31, 2021 USD ($)	Dec. 31, 2021 USD ($)
Mergers and Acquisitions
Goodwill		$ 1,924,024		$ 1,581,085
Deposits:
Goodwill		1,924,024		$ 1,581,085
Consideration:
Reversal of CSFL's ending allowance for credit losses		5,490	$ 3,374
Atlantic Capital
Mergers and Acquisitions
Shares of the common stock in exchange for each share	0.36
Purchase price	$ 657,810
Loans at fair value acquired after initial fair value adjustment	2,400,000
Estimated discount on loans	$ 48,700
Estimated discount on loans (as a percent)	2.01%
Loans acquired as a percentage of total loans	10.00%
Credit deficiencies that were identified as Purchased Credit Deteriorated ("PCD") loans.	$ 112,700
Goodwill	342,939
Acquisition costs		5,600
Assets
Cash and cash equivalents	250,158
Investment securities	703,710
Loans, net of allowance and mark	2,375,292
Premises and equipment	19,500
Intangible assets	20,791
Bank owned life insurance	74,613
Deferred tax asset	32,504
Other assets	43,997
Total assets	3,520,565
Deposits:
Noninterest-bearing	1,411,671
Interest-bearing	1,616,970
Total deposits	3,028,641
Federal funds purchased and securities sold under agreements to repurchase	50,000
Other borrowings	78,417
Other liabilities	48,636
Total liabilities	3,205,694
Net identifiable assets acquired over (under) liabilities assumed	314,871
Goodwill	342,939
Net assets acquired over liabilities assumed	$ 657,810
Consideration:
Number of shares issued as consideration | shares	7,330,803
Purchase price per share of the Company's common stock | $ / shares	$ 90.00
Company common stock issued and cash exchanged for fractional shares.	$ 659,791
Value of shares issued	659,772
Value of common stock issued for fractional shares	19
Stock option conversion	1,135
Business Acquisition Cost Of Acquired Entity Conversion Of Restricted Stock Units	2,870
Restricted stock awards conversion (unvested awards)	(5,986)
Fair value of total consideration transferred	657,810
Reversal of fair value adjustments	17,200
Securities and time deposits at fair value (discount)	30,900
HTM reclassified to AFS	$ 237,600
Credit mark of the loan portfolio (as a percent)	1.23%
Credit mark of the loan portfolio	$ 29,700
Total mark of the loan portfolio (as a percent)	2.01%
Total mark of the loan portfolio	$ 48,700
Reversal of CSFL's ending allowance for credit losses	22,100
Fair value adjustment for reversal of deferred fees and costs	7,600
Fair value adjustment for fixed assets and leased assets	2,600
Core deposit intangible from a third party valuation	$ 17,500
Core deposit intangible from a third party valuation (as a percent)	0.63
Serving assets from third party valuation	$ 3,200
Servicing assets written off	19,900
Goodwill written off	$ 2,600
Deferred tax assets related to fair value adjustments with effective tax rate	24.60%
Fair value negative adjustment for investment in low income housing	$ 1,100
Issuance costs on subordinated debt	900
Fair value adjustment on reversal of debt issuance costs	3,400
Reversal of an existing unfunded commitment reserve at purchase date	2,800
Fair value adjustment to increase lease liabilities associated with rental facilities	1,400
Fair value adjustment for reversal of uncertain tax liability	700	$ 700
Atlantic Capital | As Recorded by Atlantic Capital
Assets
Cash and cash equivalents	250,134
Investment securities	717,332
Loans, net of allowance and mark	2,394,256
Premises and equipment	16,892
Intangible assets	22,572
Bank owned life insurance	74,613
Deferred tax asset	30,231
Other assets	45,274
Total assets	3,551,304
Deposits:
Noninterest-bearing	1,411,671
Interest-bearing	1,616,970
Total deposits	3,028,641
Federal funds purchased and securities sold under agreements to repurchase	50,000
Other borrowings	74,131
Other liabilities	50,711
Total liabilities	3,203,483
Net identifiable assets acquired over (under) liabilities assumed	347,821
Net assets acquired over liabilities assumed	347,821
Atlantic Capital | Initial Fair Value Adjustments
Mergers and Acquisitions
Goodwill	342,939
Assets
Cash and cash equivalents	24
Investment securities	(13,622)
Loans, net of allowance and mark	(18,964)
Premises and equipment	2,608
Intangible assets	(1,781)
Deferred tax asset	2,273
Other assets	(1,277)
Total assets	(30,739)
Deposits:
Other borrowings	4,286
Other liabilities	(2,075)
Total liabilities	2,211
Net identifiable assets acquired over (under) liabilities assumed	(32,950)
Goodwill	342,939
Net assets acquired over liabilities assumed	$ 309,989