Mergers and acquisitions - Schedule of Recognized Identified Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Apr. 05, 2019	Jul. 31, 2017
Atlantic Capital Bank
Assets
Cash and cash equivalents	$ 207,822
Loans, net of fair value adjustments	374,399
Premises and equipment	9,650
Operating lease right-of-use assets	4,133
Core deposit intangible	10,760
Accrued interest and other assets	1,272
Total assets	608,036
Liabilities
Non-interest bearing deposits	118,405
Interest-bearing checking	112,225
Money markey and savings	211,135
Customer time deposits	147,112
Total deposits	588,877
Customer repurchase agreements	9,572
Operating lease liabilities	4,133
Accrued expenses and other liabilities	625
Total liabilities	603,207
Net assets acquired	4,829
Deposit premium	36,790
Cash and equivalents received	$ 171,032
Clayton Bank And Trust And American City Bank
Assets
Cash and cash equivalents		$ 49,059
Investment securities		59,493
FHLB stock		3,409
Loans, net of fair value adjustments		1,059,728
Premises and equipment		18,866
Other real estate owned		6,888
Core deposit and other intangibles		12,334
Other assets		5,978
Total assets		1,215,755
Liabilities
Interest-bearing deposits		670,054
Non-interest bearing deposits		309,464
Borrowings		84,831
Accrued expenses and other liabilities		5,245
Total liabilities		1,069,594
Net assets acquired		$ 146,161