Capital Ratios (Details) - USD ($) $ in Thousands		Jan. 01, 2020	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
Capital ratios
Capital conversion buffer common equity Tier 1 of risk-weighted assets (as a percent)						2.50%
Additional allowance for credit losses for loans			$ 144,785	$ 56,927	$ 56,522		$ 55,798
Deferred tax assets			46,365	$ 31,316	$ 31,884
Additional reserve for unfunded commitments			$ 8,600
Tier One Risk Based Capital to Risk Weighted Assets			12.03%	12.25%	12.85%
Capital to Risk Weighted Assets (as a percent)			12.72%	12.78%	13.35%
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets (as a percent)			8.00%	8.00%	8.00%
Common equity Tier 1 to risk-weighted assets
Actual, Capital Amount			$ 1,325,607	$ 1,326,725	$ 1,338,085
Actual, Ratio (as a percent)			11.09%	11.30%	11.86%
Minimum capital required, Ratio (as a percent)			4.50%
Required to be considered well capitalized, Capital Amount			$ 777,190	$ 763,495	$ 733,481
Required to be considered well capitalized, Ratio (as a percent)			6.50%	6.50%	6.50%
Tier I capital to risk-weighted assets
Actual, Capital Amount			$ 1,438,043	$ 1,438,995	$ 1,449,854
Actual, Ratio (as a percent)			12.03%	12.25%	12.85%
Minimum capital required, Ratio (as a percent)			6.00%	4.00%
Required to be considered well capitalized, Capital Amount			$ 956,542	$ 939,686	$ 902,746
Required to be considered well capitalized, Ratio (as a percent)			8.00%	8.00%	8.00%
Total capital to risk-weighted assets
Actual, Capital Amount			$ 1,520,966	$ 1,501,321	$ 1,506,710
Actual, Ratio (as a percent)			12.72%	12.78%	13.35%
Minimum capital required, Ratio (as a percent)			8.00%
Required to be considered well capitalized, Capital Amount			$ 1,195,677	$ 1,174,607	$ 1,128,433
Required to be considered well capitalized, Ratio (as a percent)			10.00%	10.00%	10.00%
Tier I capital to average assets (leverage ratio)
Actual, Capital Amount			$ 1,438,043	$ 1,438,995	$ 1,449,854
Actual, Ratio (as a percent)			9.56%	9.73%	10.52%
Minimum capital required, Ratio (as a percent)			4.00%
Required to be considered well capitalized, Capital Amount			$ 752,114	$ 739,664	$ 689,207
Required to be considered well capitalized, Ratio (as a percent)			5.00%	5.00%	5.00%
ASU 2016-13
Capital ratios
Additional allowance for credit losses for loans	[1]	$ 54,438
Deferred tax assets	[2]	12,639
Additional reserve for unfunded commitments		6,400
Adjustment to retained earnings		$ 44,800
Phase-In Schedule | ASU 2016-13
Capital ratios
Tier One Risk Based Capital to Risk Weighted Assets			11.56%
Capital to Risk Weighted Assets (as a percent)			12.81%
Common equity Tier 1 to risk-weighted assets
Actual, Ratio (as a percent)			10.62%
Tier I capital to risk-weighted assets
Actual, Ratio (as a percent)			11.56%
Total capital to risk-weighted assets
Actual, Ratio (as a percent)			12.81%
Tier I capital to average assets (leverage ratio)
Actual, Ratio (as a percent)			9.23%
Fully Phased-In
Common equity Tier 1 to risk-weighted assets
Minimum capital required, Capital Amount			$ 836,974	$ 822,225	$ 789,903
Minimum capital required, Ratio (as a percent)			7.00%	7.00%	7.00%
Tier I capital to risk-weighted assets
Minimum capital required, Capital Amount			$ 1,016,325	$ 998,416	$ 959,168
Minimum capital required, Ratio (as a percent)			8.50%	8.50%	8.50%
Total capital to risk-weighted assets
Minimum capital required, Capital Amount			$ 1,255,461	$ 1,233,338	$ 1,184,855
Minimum capital required, Ratio (as a percent)			10.50%	10.50%	10.50%
Tier I capital to average assets (leverage ratio)
Minimum capital required, Capital Amount			$ 601,691	$ 591,731	$ 551,366
Minimum capital required, Ratio (as a percent)			4.00%	4.00%	4.00%
South State Bank (the Bank)
Capital ratios
Tier One Risk Based Capital to Risk Weighted Assets			11.62%	12.07%	12.67%
Capital to Risk Weighted Assets (as a percent)			12.31%	12.60%	13.17%
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets (as a percent)			8.00%	8.00%	8.00%
Common equity Tier 1 to risk-weighted assets
Actual, Capital Amount			$ 1,388,822	$ 1,417,616	$ 1,429,219
Actual, Ratio (as a percent)			11.62%	12.07%	12.67%
Required to be considered well capitalized, Capital Amount			$ 777,137	$ 763,488	$ 733,448
Required to be considered well capitalized, Ratio (as a percent)			6.50%	6.50%	6.50%
Tier I capital to risk-weighted assets
Actual, Capital Amount			$ 1,388,822	$ 1,417,616	$ 1,429,219
Actual, Ratio (as a percent)			11.62%	12.07%	12.67%
Required to be considered well capitalized, Capital Amount			$ 956,476	$ 939,677	$ 902,706
Required to be considered well capitalized, Ratio (as a percent)			8.00%	8.00%	8.00%
Total capital to risk-weighted assets
Actual, Capital Amount			$ 1,471,745	$ 1,479,942	$ 1,486,075
Actual, Ratio (as a percent)			12.31%	12.60%	13.17%
Required to be considered well capitalized, Capital Amount			$ 1,195,595	$ 1,174,597	$ 1,128,382
Required to be considered well capitalized, Ratio (as a percent)			10.00%	10.00%	10.00%
Tier I capital to average assets (leverage ratio)
Actual, Capital Amount			$ 1,388,822	$ 1,417,616	$ 1,429,219
Actual, Ratio (as a percent)			9.24%	9.59%	10.37%
Required to be considered well capitalized, Capital Amount			$ 751,912	$ 739,490	$ 689,022
Required to be considered well capitalized, Ratio (as a percent)			5.00%	5.00%	5.00%
South State Bank (the Bank) | Fully Phased-In
Common equity Tier 1 to risk-weighted assets
Minimum capital required, Capital Amount			$ 836,917	$ 822,218	$ 789,867
Minimum capital required, Ratio (as a percent)			7.00%	7.00%	7.00%
Tier I capital to risk-weighted assets
Minimum capital required, Capital Amount			$ 1,016,256	$ 998,407	$ 959,125
Minimum capital required, Ratio (as a percent)			8.50%	8.50%	8.50%
Total capital to risk-weighted assets
Minimum capital required, Capital Amount			$ 1,255,375	$ 1,233,327	$ 1,184,801
Minimum capital required, Ratio (as a percent)			10.50%	10.50%	10.50%
Tier I capital to average assets (leverage ratio)
Minimum capital required, Capital Amount			$ 601,530	$ 591,592	$ 551,218
Minimum capital required, Ratio (as a percent)			4.00%	4.00%	4.00%

[1] This is the calculated adjustment to the ACL related to the adoption of ASC 326. Additional reserve related to non-acquired loans was $34,049, to acquired loans was $16,981 and to purchased credit deteriorated loans was $3,408.

[2] This is the effect of deferred tax assets related to the adjustment to the ACL from the adoption of ASC 326 using a 22% tax rate.