Capital Ratios (Details) - USD ($) $ in Thousands	Jan. 01, 2019	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017
Common equity Tier 1 to risk-weighted assets
Actual, Capital Amount		$ 1,356,267	$ 1,273,547	$ 1,013,065
Actual, Ratio (as a percent)		12.30%	11.59%	12.11%
Minimum capital required, Ratio (as a percent)		4.50%
Required to be considered well capitalized, Capital Amount		$ 716,764	$ 714,221	$ 543,709
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		$ 1,467,703	$ 1,384,433	$ 1,084,145
Actual, Ratio (as a percent)		13.31%	12.60%	12.96%
Minimum capital required, Ratio (as a percent)		6.00%	4.00%
Required to be considered well capitalized, Capital Amount		$ 882,170	$ 879,042	$ 669,180
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		$ 1,521,875	$ 1,432,843	$ 1,129,742
Actual, Ratio (as a percent)		13.80%	13.04%	13.51%
Minimum capital required, Ratio (as a percent)		8.00%
Required to be considered well capitalized, Capital Amount		$ 1,102,713	$ 1,098,802	$ 836,475
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		$ 1,467,703	$ 1,384,433	$ 1,084,145
Actual, Ratio (as a percent)		10.82%	10.36%	10.34%
Minimum capital required, Ratio (as a percent)		4.00%
Required to be considered well capitalized, Capital Amount		$ 678,401	$ 668,075	$ 524,082
Required to be considered well capitalized, Ratio (as a percent)		5.00%	5.00%	5.00%
Phase-In Schedule
Common equity Tier 1 to risk-weighted assets
Minimum capital required, Capital Amount		$ 702,980	$ 631,811	$ 480,973
Minimum capital required, Ratio (as a percent)		6.38%	5.75%	5.75%
Tier I capital to risk-weighted assets
Minimum capital required, Capital Amount		$ 868,387	$ 796,632	$ 606,444
Minimum capital required, Ratio (as a percent)		7.88%	7.25%	7.25%
Total capital to risk-weighted assets
Minimum capital required, Capital Amount		$ 1,088,929	$ 1,016,392	$ 773,739
Minimum capital required, Ratio (as a percent)		9.88%	9.25%	9.25%
Tier I capital to average assets (leverage ratio)
Minimum capital required, Capital Amount		$ 542,720	$ 534,460	$ 419,265
Minimum capital required, Ratio (as a percent)		4.00%	4.00%	4.00%
Fully Phased-In
Common equity Tier 1 to risk-weighted assets
Minimum capital required, Capital Amount		$ 771,899	$ 769,162	$ 585,532
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		$ 937,306	$ 933,982	$ 711,004
Minimum capital required, Ratio (as a percent)		8.50%	8.50%	8.50%
Total capital to risk-weighted assets
Minimum capital required, Capital Amount		$ 1,157,849	$ 1,153,742	$ 878,299
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		$ 542,720	$ 534,460	$ 419,265
Minimum capital required, Ratio (as a percent)		4.00%	4.00%	4.00%
Subsequent event
Capital ratios
Capital conversion buffer common equity Tier 1 of risk-weighted assets (as a percent)	2.50%
South State Bank (the Bank)
Common equity Tier 1 to risk-weighted assets
Actual, Capital Amount		$ 1,449,326	$ 1,360,603	$ 1,050,203
Actual, Ratio (as a percent)		13.14%	12.38%	12.56%
Required to be considered well capitalized, Capital Amount		$ 716,834	$ 714,143	$ 543,713
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		$ 1,449,326	$ 1,360,603	$ 1,050,203
Actual, Ratio (as a percent)		13.14%	12.38%	12.56%
Required to be considered well capitalized, Capital Amount		$ 882,258	$ 878,945	$ 669,185
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		$ 1,503,498	$ 1,409,014	$ 1,095,624
Actual, Ratio (as a percent)		13.63%	12.82%	13.10%
Required to be considered well capitalized, Capital Amount		$ 1,102,822	$ 1,098,681	$ 836,481
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		$ 1,449,326	$ 1,360,603	$ 1,050,203
Actual, Ratio (as a percent)		10.68%	10.18%	10.02%
Required to be considered well capitalized, Capital Amount		$ 678,219	$ 667,987	$ 523,935
Required to be considered well capitalized, Ratio (as a percent)		5.00%	5.00%	5.00%
South State Bank (the Bank) | Phase-In Schedule
Common equity Tier 1 to risk-weighted assets
Minimum capital required, Capital Amount		$ 703,049	$ 631,741	$ 480,977
Minimum capital required, Ratio (as a percent)		6.38%	5.75%	5.75%
Tier I capital to risk-weighted assets
Minimum capital required, Capital Amount		$ 868,472	$ 796,544	$ 606,449
Minimum capital required, Ratio (as a percent)		7.88%	7.25%	7.25%
Total capital to risk-weighted assets
Minimum capital required, Capital Amount		$ 1,089,037	$ 1,016,280	$ 773,745
Minimum capital required, Ratio (as a percent)		9.88%	9.25%	9.25%
Tier I capital to average assets (leverage ratio)
Minimum capital required, Capital Amount		$ 542,575	$ 534,390	$ 419,148
Minimum capital required, Ratio (as a percent)		4.00%	4.00%	4.00%
South State Bank (the Bank) | Fully Phased-In
Common equity Tier 1 to risk-weighted assets
Minimum capital required, Capital Amount		$ 771,975	$ 769,077	$ 585,537
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		$ 937,399	$ 933,879	$ 711,009
Minimum capital required, Ratio (as a percent)		8.50%	8.50%	8.50%
Total capital to risk-weighted assets
Minimum capital required, Capital Amount		$ 1,157,963	$ 1,153,615	$ 878,305
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		$ 542,575	$ 534,390	$ 419,148
Minimum capital required, Ratio (as a percent)		4.00%	4.00%	4.00%