Business Combination - Additional Information (Details) $ in Thousands		3 Months Ended
	Jan. 01, 2019 USD ($) BranchLocation shares	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Business Acquisition [Line Items]
Goodwill		$ 480,391	$ 307,083
Discount on acquired non-credit impaired loans	$ 74,800	85,289	35,194
Unfunded commitments		43,200	$ 37,500
Merger related costs		22,000
State Bank Financial Corporation
Business Acquisition [Line Items]
Shares issued for business acquisition | shares	49,232,008
Purchase price consideration	$ 826,400
Value of common stock in purchase price	826,113
Cash representing the value of outstanding warrants	300
Loans added in acquisition	3,324,056	3,500,000
Deposits added in acquisition	4,096,665	4,100,000
Goodwill	173,308
Fair value of acquired non-credit impaired (“ANCI”) loans acquired	3,200,000
Contractual amounts receivable of ANCI loans	3,900,000
Contractual cash flows not expected to be collected	$ 200,000
Unfunded commitments		26,800
Merger related costs		$ 22,000
State Bank Financial Corporation | Certificates of Deposit
Business Acquisition [Line Items]
Estimated useful life	12 months
Discount on transaction of certificates of deposit	$ 3,400
State Bank Financial Corporation | Banking Segment
Business Acquisition [Line Items]
Goodwill	173,300
State Bank Financial Corporation | Core Deposit
Business Acquisition [Line Items]
Intangible assets recognized	$ 111,900
Estimated useful life	10 years
State Bank Financial Corporation | Customer Relationship
Business Acquisition [Line Items]
Intangible assets recognized	$ 3,700
Estimated useful life	10 years
State Bank Financial Corporation | Trademark
Business Acquisition [Line Items]
Intangible assets recognized	$ 1,400
Estimated useful life	20 years
State Bank Financial Corporation | Northern and Central Georgia
Business Acquisition [Line Items]
Number of branch locations | BranchLocation	32
State Bank Financial Corporation | Common Class A
Business Acquisition [Line Items]
Common stock in exchange for outstanding common shares | shares	1.271
Shares issued for business acquisition | shares	49,200,000