Covered Assets and Indemnification Asset - Covered Loans Summary (Details) $ in Thousands	Sep. 13, 2013 USD ($)	Sep. 30, 2017 USD ($) item	Dec. 31, 2016 USD ($)
Covered Loans
Allowance for covered loans		$ (2,141)	$ (413)
Total covered loans, net of allowance		188,269	255,714
Covered
Covered Loans
Total covered loans		190,410	256,127
Allowance for covered loans		(2,141)	(413)
Total covered loans, net of allowance		188,269	255,714
Covered | Commercial and industrial
Covered Loans
Total covered loans		1,242	2,697
Covered | Real estate
Covered Loans
Total covered loans		186,777	244,469
Covered | Construction and land development
Covered Loans
Total covered loans		$ 2,391	$ 8,961
Covered | Acquired loans
Loans
Fair value of loans acquired	$ 1,100,000
Carryover of the allowance for loan losses recorded	$ 0
Minimum number of layers of common risk | item		2