Loans and Allowance for Loan Losses - Table of loan payment estimates - (Details) - USD ($) $ in Thousands			12 Months Ended
	Nov. 30, 2017	Jan. 03, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Park Sterling Corporation
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Contractual principal and interest	$ 92,600
Non-accretable difference	(12,840)
Cash flows expected to be collected	79,760
Accretable difference	(8,829)
Carrying value	70,931
Acquired credit impaired loans
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Contractual principal and interest			$ 795,850	$ 778,822
Non-accretable difference			(39,324)	(17,502)
Cash flows expected to be collected			756,526	761,320
Accretable difference			(133,096)	(155,379)
Carrying value			623,430	605,941	$ 737,576
Allowance for loan losses on acquired loans			(4,627)	(3,395)	(3,706)	$ (7,365)
Acquired non-credit impaired loans accounted under FASB 310 20
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value			3,507,907	836,699
Acquired non-credit impaired loans accounted under FASB 310 20 | Park Sterling Corporation
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Contractual principal and interest	2,300,000
After fair value adjustment	2,200,000
Fair value adjustment	$ 50,100
Acquired credit impaired loans accounted under FASB 310 30
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value			623,430	605,941
Allowance for loan losses on acquired loans			(4,627)	(3,395)
Acquired loans accounted under FASB ASC 310 20
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Contractual principal and interest			3,600,000	848,300
After fair value adjustment			3,500,000	836,700
Fair value adjustment			65,400	11,600
Acquired credit impaired and non-impaired loans accounted Under FASB ASC Topic 310-30 | Southeastern Bank Financial
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Contractual principal and interest		$ 73,365
Non-accretable difference		(12,912)
Cash flows expected to be collected		60,453
Accretable difference		(4,603)
Carrying value		55,850
Acquired credit impaired and non-impaired loans accounted under FASB ASC Topic 310-20 | Southeastern Bank Financial
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Contractual principal and interest		1,010,000
After fair value adjustment		991,500
Fair value adjustment		$ 18,800
Acquired non-credit impaired loans
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value			3,507,907	836,699
Residential real estate
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value			260,787	258,100
Residential real estate | Acquired credit impaired loans
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value			260,787	258,100	313,319
Allowance for loan losses on acquired loans			(3,553)	(2,419)	(2,986)	(4,387)
Residential real estate | Acquired credit impaired loans accounted under FASB 310 30
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value			260,787	258,100
Commercial non-owner occupied real estate | Acquired non-credit impaired loans accounted under FASB 310 20
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value			1,220,523	44,718
Commercial owner occupied real estate loan | Acquired non-credit impaired loans accounted under FASB 310 20
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value			521,818	27,195
Commercial owner occupied real estate loan | Acquired non-credit impaired loans
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value			521,818	27,195
Consumer real estate | Acquired credit impaired loans
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value			51,453	59,300	70,734
Allowance for loan losses on acquired loans			(461)	(558)	(313)	(275)
Consumer real estate | Acquired non-credit impaired loans accounted under FASB 310 20
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value			1,031,202	569,149
Consumer real estate | Acquired non-credit impaired loans
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value			1,170,201	711,803
Commercial and industrial
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value			26,946	25,347
Commercial and industrial | Acquired credit impaired loans
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value			26,946	25,347	31,193
Allowance for loan losses on acquired loans			(145)	(238)	(174)	(718)
Commercial and industrial | Acquired non-credit impaired loans accounted under FASB 310 20
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value			398,696	13,641
Commercial and industrial | Acquired credit impaired loans accounted under FASB 310 30
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value			26,946	25,347
Commercial and industrial | Acquired non-credit impaired loans
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value			398,696	13,641
Other income producing property | Acquired non-credit impaired loans accounted under FASB 310 20
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value			196,669	39,342
Other income producing property | Acquired non-credit impaired loans
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value			196,669	39,342
Consumer
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value			51,453	59,300
Consumer | Acquired credit impaired loans
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value			51,453	59,300
Consumer | Acquired non-credit impaired loans accounted under FASB 310 20
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value			137,710	142,654
Consumer | Acquired credit impaired loans accounted under FASB 310 30
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value			51,453	59,300
Consumer | Acquired non-credit impaired loans
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value			137,710	142,654
Commercial | Acquired non-credit impaired loans
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value			2,337,706	124,896
Single pay loans | Acquired credit impaired loans
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Allowance for loan losses on acquired loans						(70)
Other loans
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value			1,289
Other loans | Acquired non-credit impaired loans accounted under FASB 310 20
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value			1,289
Other loans | Acquired non-credit impaired loans
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value			1,289
Construction and land development | Commercial non-owner occupied real estate | Acquired credit impaired loans
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value			49,649	44,373	54,272
Allowance for loan losses on acquired loans			(180)	(139)	(177)	(336)
Construction and land development | Commercial non-owner occupied real estate | Acquired non-credit impaired loans accounted under FASB 310 20
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value			403,357	10,090
Construction and land development | Commercial non-owner occupied real estate | Acquired credit impaired loans accounted under FASB 310 30
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value			49,649	44,373
Construction and land development | Commercial non-owner occupied real estate | Acquired non-credit impaired loans
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value			403,357	10,090
Other commercial non-owner occupied real estate | Commercial non-owner occupied real estate | Acquired credit impaired loans
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value			234,595	218,821	268,058
Allowance for loan losses on acquired loans			(288)	(41)	$ (56)	$ (1,579)
Other commercial non-owner occupied real estate | Commercial non-owner occupied real estate | Acquired non-credit impaired loans accounted under FASB 310 20
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value			817,166	34,628
Other commercial non-owner occupied real estate | Commercial non-owner occupied real estate | Acquired credit impaired loans accounted under FASB 310 30
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value			234,595	218,821
Other commercial non-owner occupied real estate | Commercial non-owner occupied real estate | Acquired non-credit impaired loans
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value			817,166	34,628
Home equity loans | Consumer real estate | Acquired non-credit impaired loans accounted under FASB 310 20
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value			320,591	160,879
Home equity loans | Consumer real estate | Acquired non-credit impaired loans
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value			320,591	160,879
Other Consumer | Consumer real estate | Acquired non-credit impaired loans
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value			137,710	142,654
Consumer Owner Occupied Loans | Consumer real estate | Acquired non-credit impaired loans accounted under FASB 310 20
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value			710,611	408,270
Consumer Owner Occupied Loans | Consumer real estate | Acquired non-credit impaired loans
Contractual loan payments receivable, estimates of amounts not expected to be collected, other fair value adjustments and the resulting fair values of acquired loans
Carrying value			$ 710,611	$ 408,270