Mergers and Acquisitions - Additional Information (Detail) $ / shares in Units, $ in Thousands			2 Months Ended	3 Months Ended	6 Months Ended
	May 01, 2020 USD ($) $ / shares shares	Nov. 17, 2019 $ / shares	Jun. 30, 2020 USD ($) $ / shares	Jun. 30, 2020 USD ($) $ / shares	Jun. 30, 2020 USD ($) $ / shares	Dec. 31, 2019 USD ($) $ / shares
Business Acquisition [Line Items]
Par value of Share | $ / shares			$ 2.50	$ 2.50	$ 2.50	$ 2.50
Total assets at consummation			$ 26,234,973	$ 26,234,973	$ 26,234,973	$ 19,662,324
Loans at consummation			18,032,554	18,032,554	18,032,554	$ 13,713,548
Business combination intangible assets acquired goodwill					316,765
Business acquisition allowances for loans and lease losses including reserve for unfunded commitments for assets with credit deterioration				$ 18,635	$ 18,635
Carolina Financial [Member]
Business Acquisition [Line Items]
Conversion of Option to acquire common stock exchange ratio		1.13
Business Acquisition, Share Price | $ / shares	$ 29.11
Conversion of stock award to acquire common stock exchange ratio		1.13
Total assets at consummation	$ 5,005,744
Loans at consummation	3,292,635
Deposits at consummation	3,873,183
Business combination aggregate purchase consideration	817,877
Business combination purchase consideration equity shares issued or issuable value	815,997
Business combination stock options issued	1,833
Business combination cash consideration	$ 47
Business combination number of shares issued | shares	28,031,501
Business combination intangible assets acquired goodwill	$ 316,765
Business combination intangible assets acquired other than goodwill core deposit intangibles finite lived	3,037
Business combination intangible assets acquired other than goodwill indefinite lived	1,370
Business combination expected tax deductible goodwill	0
Business acquisition loans purchase deterioration credit loans acquired discount due to diiferences in purchase consideration	$ 10,259
Business acquisition weighted average remaining useful life of purchase credit deterioration of loans					4 years 7 months 6 days
Business acquisition weighted average remaining useful life of non purchase credit deterioration of loans					7 years 3 months 18 days
Business acquisition revenue of the acquiree included in the total revenue since the date of acquisition			40,419
Business acquisition net income of the acquiree included in the total revenue since the date of acquisition			$ 22,858
Business acquisition, percentage of voting interests acquired	100.00%
Business acquisition allowances for loans and lease losses including reserve for unfunded commitments for assets with credit deterioration	$ 18,635
Carolina Financial [Member] | Including Unfunded Commitements [Member]
Business Acquisition [Line Items]
Business acquisition allowances for loans and lease losses including reserve for unfunded commitments	50,562
Business acquisition allowances for loans and lease losses including reserve for unfunded commitments for assets with credit deterioration	19,797
Carolina Financial [Member] | Loans Acquired [Member]
Business Acquisition [Line Items]
Business combination fair value adjustment to purchase consideration	51,553
Carolina Financial [Member] | Securities Investment [Member]
Business Acquisition [Line Items]
Business combination fair value adjustment to purchase consideration	562
Carolina Financial [Member] | Financial Asset, Other than Financial Asset Acquired with Credit Deterioration [Member]
Business Acquisition [Line Items]
Business acquisition fair value of non purchase credit deteroration loans acquired	41,294
Business acquisition increase in expected credit losses	28,948
Carolina Financial [Member] | Financial Asset, Other than Financial Asset Acquired with Credit Deterioration [Member] | Including Unfunded Commitements [Member]
Business Acquisition [Line Items]
Business acquisition allowances for loans and lease losses including reserve for unfunded commitments	30,765
Carolina Financial [Member] | Interest-bearing Deposits [Member]
Business Acquisition [Line Items]
Business combination fair value adjustment to purchase consideration	12,818
Business combination interest bearing deposits acquired remaining term on the premium paid					5 years 1 month 6 days
Carolina Financial [Member] | Building [Member]
Business Acquisition [Line Items]
Business combination fair value adjustment to purchase consideration	8,848
Business combination finite lived tangible assets remaining useful life on premium paid					31 years 6 months
Carolina Financial [Member] | Other Real Estate Owned [Member]
Business Acquisition [Line Items]
Business combination fair value adjustment to purchase consideration	272
Carolina Financial [Member] | Land [Member]
Business Acquisition [Line Items]
Business combination fair value adjustment to purchase consideration	4,960
Carolina Financial [Member] | Trust Preferred Securities Subject to Mandatory Redemption [Member]
Business Acquisition [Line Items]
Business combination fair value adjustment to purchase consideration	4,831
Business combination unamortized discount on trust preferred securities					16 years 9 months 29 days
Carolina Financial [Member] | Subordinated Debt [Member]
Business Acquisition [Line Items]
Business combination fair value adjustment to purchase consideration	135
Business combination unamortized discount on debt useful life					6 years 9 months
Carolina Financial [Member] | Federal Home Loan Bank Advances [Member]
Business Acquisition [Line Items]
Business combination fair value adjustment to purchase consideration	$ 468
Business combination unamortized discount on debt useful life					6 months 29 days
Carolina Financial [Member] | Common Stock [Member]
Business Acquisition [Line Items]
Stock issued during period merger conversion ratio		1.13
Par value of Share | $ / shares		$ 2.50
Series of Individually Immaterial Business Acquisitions [Member] | Common Stock [Member]
Business Acquisition [Line Items]
Business Acquisition, Share Price | $ / shares		$ 28.99