Non-Covered Loans and Allowance for Non-Covered Loan Losses - Summary (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Loans
Total loans	$ 6,216,809	$ 6,273,669
Allowance for loan losses	(60,371)	(60,957)
Non-covered loans, net	6,156,438	6,212,712
Noncovered
Loans
Total loans	6,216,809	6,273,669
Allowance for loan losses	(60,371)	(60,957)	$ (55,157)	$ (54,186)
Non-covered loans, net	6,156,438	6,212,712
Noncovered \| Commercial and industrial
Loans
Total loans	1,650,096	1,681,205
Allowance for loan losses	(23,269)	(23,674)	(21,679)	(21,369)
Noncovered \| Real estate
Loans
Total loans	3,051,603	3,011,524
Allowance for loan losses	(29,300)	(28,775)	(26,112)	(25,236)
Noncovered \| Construction and land development
Loans
Total loans	929,708	962,605
Allowance for loan losses	(7,449)	(7,844)	(6,879)	(7,002)
Noncovered \| Consumer
Loans
Total loans	38,898	40,446
Allowance for loan losses	(276)	(311)	(464)	(424)
Noncovered \| Broker-dealer
Loans
Total loans	546,504	577,889
Allowance for loan losses	$ (77)	$ (353)	$ (23)	$ (155)

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Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

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Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

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Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements and loans held for sale.

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