Loans - Summary of loans (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019	Jun. 30, 2019
Summary of Loans
Total loans - ASU 2016-13	$ 25,499,147
Total loans		$ 11,375,104	$ 11,226,192
Less allowance for credit losses	(434,608)	(56,927)	(53,590)
Loans, net	25,064,539	11,313,113	11,167,979
Deferred costs	64,700
Unamortized Discounts	160,800
Accrued interest receivable (AIR)	94,500
Acquired credit impaired loans
Summary of Loans
Total loans		361,846	424,584
Less allowance for credit losses		(5,064)	(4,623)
Loans, net		356,782	419,961
Previous Accounting Guidance [Member]
Summary of Loans
Less allowance for credit losses		(61,991)	(58,213)
Construction and land development
Summary of Loans
Total loans - ASU 2016-13	1,999,062
Total loans		1,017,261	957,346
Consumer Owner Occupied Loans
Summary of Loans
Total loans - ASU 2016-13	4,421,247
Total loans		2,706,960	2,762,266
Other income producing property
Summary of Loans
Total loans - ASU 2016-13	650,237
Total loans		346,554	367,353
Commercial loans
Summary of Loans
Total loans - ASU 2016-13	18,075,732
Commercial loans | Construction and land development
Summary of Loans
Total loans - ASU 2016-13	1,305,510
Commercial loans | Construction and land development | Acquired credit impaired loans
Summary of Loans
Total loans		25,032	27,014
Commercial loans | Commercial non-owner occupied
Summary of Loans
Total loans - ASU 2016-13	6,021,317
Total loans		2,323,967	2,398,249
Commercial loans | Commercial non-owner occupied real estate
Summary of Loans
Total loans - ASU 2016-13	8,020,379
Total loans		3,341,228	3,355,595
Commercial loans | Consumer Owner Occupied Loans
Summary of Loans
Total loans - ASU 2016-13	38,387
Commercial loans | Real estate | Acquired credit impaired loans
Summary of Loans
Total loans		130,938	164,540
Commercial loans | Commercial owner occupied real estate loan
Summary of Loans
Total loans - ASU 2016-13	4,762,520
Total loans		2,158,701	2,047,933
Commercial loans | Commercial and industrial
Summary of Loans
Total loans - ASU 2016-13	5,341,363
Total loans		1,386,327	1,271,464
Commercial loans | Commercial and industrial | Acquired credit impaired loans
Summary of Loans
Total loans		7,029	10,198
Commercial loans | Other income producing property
Summary of Loans
Total loans - ASU 2016-13	598,263
Commercial loans | Other loans
Summary of Loans
Total loans - ASU 2016-13	8,372
Total loans		13,892	1,601
Consumer
Summary of Loans
Total loans - ASU 2016-13	7,423,415
Consumer | Construction and land development
Summary of Loans
Total loans - ASU 2016-13	693,552
Consumer | Consumer Owner Occupied Loans
Summary of Loans
Total loans - ASU 2016-13	4,382,860
Consumer | Home equity loans
Summary of Loans
Total loans - ASU 2016-13	1,378,406
Total loans		758,020	778,234
Consumer | Real estate
Summary of Loans
Total loans - ASU 2016-13	5,799,653
Total loans		3,464,980	3,540,500
Consumer | Real estate | Acquired credit impaired loans
Summary of Loans
Total loans		163,359	184,208
Consumer | Other income producing property
Summary of Loans
Total loans - ASU 2016-13	51,974
Consumer | Consumer
Summary of Loans
Total loans - ASU 2016-13	$ 916,623
Total loans		663,422	641,746
Consumer | Consumer | Acquired credit impaired loans
Summary of Loans
Total loans		$ 35,488	$ 38,624