Mergers and Acquisitions - Atlantic Capital (Details)		3 Months Ended		12 Months Ended
	Mar. 01, 2022 USD ($) $ / shares shares	Mar. 31, 2023 USD ($)	Mar. 31, 2022 USD ($)	Dec. 31, 2022 USD ($)
Mergers and Acquisitions
Goodwill		$ 1,923,106,000		$ 1,923,106,000
Deposits:
Goodwill		1,923,106,000		1,923,106,000
Consideration:
Reversal of CSFL's ending allowance for credit losses		4,627,000	$ 5,490,000	$ 23,446,000
Atlantic Capital
Mergers and Acquisitions
Shares of the common stock in exchange for each share	0.36
Purchase price	$ 657,810,000
Loans at fair value acquired after initial fair value adjustment	2,400,000,000
Estimated discount on loans	$ 54,300,000
Estimated discount on loans (as a percent)	2.24%
Loans acquired as a percentage of total loans	10.00%
Credit deficiencies that were identified as Purchased Credit Deteriorated ("PCD") loans.	$ 137,900,000
Goodwill	342,021,000
Acquisition costs		$ 1,400,000	$ 5,600,000
Assets
Cash and cash equivalents	250,158,000
Investment securities	703,710,000
Loans, net of allowance and mark	2,369,678,000
Premises and equipment	19,500,000
Intangible assets	20,791,000
Bank owned life insurance	74,613,000
Deferred tax asset	31,479,000
Other assets	51,554,000
Total assets	3,521,483,000
Deposits:
Noninterest-bearing	1,411,671,000
Interest-bearing	1,616,970,000
Total deposits	3,028,641,000
Federal funds purchased and securities sold under agreements to repurchase	50,000,000
Other borrowings	78,417,000
Other liabilities	48,636,000
Total liabilities	3,205,694,000
Net identifiable assets acquired over (under) liabilities assumed	315,789,000
Goodwill	342,021,000
Net assets acquired over liabilities assumed	$ 657,810,000
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.	$ 659,791,000
Value of shares issued	659,772,000
Value of common stock issued for fractional shares	19,000
Stock option conversion	1,135,000
Restricted stock unit conversion	2,870,000
Restricted stock awards conversion (unvested awards)	(5,986,000)
Fair value of total consideration transferred	657,810,000
Reversal of fair value adjustments	17,200,000
Securities and time deposits at fair value (discount)	30,900,000
HTM reclassified to AFS	$ 237,600,000
Credit mark of the loan portfolio (as a percent)	1.40%
Credit mark of the loan portfolio	$ 34,000,000.0
Net credit discount of the loan portfolio (as a percent)	2.24%
Net non-credit discount of the loan portfolio	$ 54,300,000
Reversal of CSFL's ending allowance for credit losses	22,100,000
Fair value adjustment for reversal of deferred fees and costs	7,600,000
Fair value adjustment for fixed assets and leased assets	2,600,000
Core deposit intangible from a third party valuation	$ 17,500,000
Core deposit intangible from a third party valuation (as a percent)	0.63
Serving assets from third party valuation	$ 3,200,000
Servicing assets written off	19,900,000
Goodwill written off	$ 2,600,000
Deferred tax assets related to fair value adjustments with marginal tax rate	23.90%
Fair value negative adjustment for investment in low income housing	$ 1,100,000
Fair value adjustment (decrease) on write-off of prepaid assets	233,000
Fair value adjustment for receivables	154,000
Fair value adjustment for Small Business Investment Company ("SBIC') Investments	7,400,000
Issuance costs on subordinated debt	900,000
Fair value adjustment on reversal of debt issuance costs	3,400,000
Reversal of an existing unfunded commitment reserve at purchase date	2,800,000
Fair value adjustment to increase lease liabilities associated with rental facilities	1,400,000
Fair value adjustment for reversal of uncertain tax liability	700,000
Atlantic Capital | As Recorded by Atlantic Capital
Assets
Cash and cash equivalents	250,134,000
Investment securities	717,332,000
Loans, net of allowance and mark	2,394,256,000
Premises and equipment	16,892,000
Intangible assets	22,572,000
Bank owned life insurance	74,613,000
Deferred tax asset	30,231,000
Other assets	45,274,000
Total assets	3,551,304,000
Deposits:
Noninterest-bearing	1,411,671,000
Interest-bearing	1,616,970,000
Total deposits	3,028,641,000
Federal funds purchased and securities sold under agreements to repurchase	50,000,000
Other borrowings	74,131,000
Other liabilities	50,711,000
Total liabilities	3,203,483,000
Net identifiable assets acquired over (under) liabilities assumed	347,821,000
Net assets acquired over liabilities assumed	347,821,000
Atlantic Capital | Initial Fair Value Adjustments
Mergers and Acquisitions
Goodwill	342,939,000
Assets
Cash and cash equivalents	24,000
Investment securities	(13,622,000)
Loans, net of allowance and mark	(18,964,000)
Premises and equipment	2,608,000
Intangible assets	(1,781,000)
Deferred tax asset	2,273,000
Other assets	(1,277,000)
Total assets	(30,739,000)
Deposits:
Other borrowings	4,286,000
Other liabilities	(2,075,000)
Total liabilities	2,211,000
Net identifiable assets acquired over (under) liabilities assumed	(32,950,000)
Goodwill	342,939,000
Net assets acquired over liabilities assumed	309,989,000
Atlantic Capital | Subsequent Fair Value Adjustments
Mergers and Acquisitions
Goodwill	(918,000)
Assets
Loans, net of allowance and mark	(5,614,000)
Deferred tax asset	(1,025,000)
Other assets	7,557,000
Total assets	918,000
Deposits:
Net identifiable assets acquired over (under) liabilities assumed	918,000
Goodwill	$ (918,000)