Capital Ratios (Details) - USD ($) $ in Thousands	Jan. 01, 2019	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Common equity Tier 1 to risk-weighted assets
Actual, Capital Amount		$ 1,295,729	$ 1,273,547	$ 959,802
Actual, Ratio (as a percent)		11.85%	11.59%	11.90%
Minimum capital required, Ratio (as a percent)		4.50%
Required to be considered well capitalized, Capital Amount		$ 710,909	$ 714,221	$ 524,356
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		$ 1,406,832	$ 1,384,433	$ 1,030,559
Actual, Ratio (as a percent)		12.86%	12.60%	12.77%
Minimum capital required, Ratio (as a percent)		6.00%	4.00%
Required to be considered well capitalized, Capital Amount		$ 874,964	$ 879,042	$ 645,362
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		$ 1,456,453	$ 1,432,843	$ 1,074,107
Actual, Ratio (as a percent)		13.32%	13.04%	13.31%
Minimum capital required, Ratio (as a percent)		8.00%
Required to be considered well capitalized, Capital Amount		$ 1,093,706	$ 1,098,802	$ 806,702
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		$ 1,406,832	$ 1,384,433	$ 1,030,559
Actual, Ratio (as a percent)		10.50%	10.36%	10.05%
Minimum capital required, Ratio (as a percent)		4.00%
Required to be considered well capitalized, Capital Amount		$ 669,654	$ 668,075	$ 512,567
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		$ 697,237	$ 631,811	$ 463,854
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		$ 861,293	$ 796,632	$ 584,859
Minimum capital required, Ratio (as a percent)		7.88%	7.25%	7.25%
Total capital to risk-weighted assets
Minimum capital required, Capital Amount		$ 1,080,034	$ 1,016,392	$ 746,199
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		$ 535,724	$ 534,460	$ 410,054
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		$ 765,594	$ 769,162	$ 564,691
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		$ 929,650	$ 933,982	$ 685,697
Minimum capital required, Ratio (as a percent)		8.50%	8.50%	8.50%
Total capital to risk-weighted assets
Minimum capital required, Capital Amount		$ 1,148,391	$ 1,153,742	$ 847,037
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		$ 535,724	$ 534,460	$ 410,054
Minimum capital required, Ratio (as a percent)		4.00%	4.00%	4.00%
Forecast
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		$ 1,385,289	$ 1,360,603	$ 998,061
Actual, Ratio (as a percent)		12.67%	12.38%	12.37%
Required to be considered well capitalized, Capital Amount		$ 710,925	$ 714,143	$ 524,259
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		$ 1,385,289	$ 1,360,603	$ 998,061
Actual, Ratio (as a percent)		12.67%	12.38%	12.37%
Required to be considered well capitalized, Capital Amount		$ 874,985	$ 878,945	$ 645,241
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		$ 1,434,911	$ 1,409,014	$ 1,041,277
Actual, Ratio (as a percent)		13.12%	12.82%	12.91%
Required to be considered well capitalized, Capital Amount		$ 1,093,731	$ 1,098,681	$ 806,552
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		$ 1,385,289	$ 1,360,603	$ 998,061
Actual, Ratio (as a percent)		10.35%	10.18%	9.75%
Required to be considered well capitalized, Capital Amount		$ 669,402	$ 667,987	$ 511,959
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		$ 697,253	$ 631,741	$ 463,767
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		$ 861,313	$ 796,544	$ 584,750
Minimum capital required, Ratio (as a percent)		7.88%	7.25%	7.25%
Total capital to risk-weighted assets
Minimum capital required, Capital Amount		$ 1,080,059	$ 1,016,280	$ 746,060
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		$ 535,522	$ 534,390	$ 409,567
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		$ 765,612	$ 769,077	$ 564,586
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		$ 929,671	$ 933,879	$ 685,569
Minimum capital required, Ratio (as a percent)		8.50%	8.50%	8.50%
Total capital to risk-weighted assets
Minimum capital required, Capital Amount		$ 1,148,417	$ 1,153,615	$ 846,879
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		$ 535,522	$ 534,390	$ 409,567
Minimum capital required, Ratio (as a percent)		4.00%	4.00%	4.00%