Regulatory Matters - Minimum Capital Requirements (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Dec. 31, 2019
Regulatory matters
Regulatory capital effects from CECL transitionary period	5 years
PlainsCapital (the Bank)
Tier 1 capital (to average assets)
Actual Amount	$ 1,333,686	$ 1,236,289
Actual Ratio (as a percent)	10.37%	11.61%
Minimum Capital Requirement Including Conservation Buffer fully phased-in, ratio (as a percent)	4.00%	4.00%
To Be Well Capitalized Minimum Capital Requirements, Ratio (as a percent)	5.00%	5.00%
Common equity Tier 1 capital (to risk weighted assets)
Actual Amount	$ 1,333,686	$ 1,236,289
Actual Ratio (as a percent)	14.03%	13.45%
Minimum Capital Requirement Including Conservation Buffer fully phased-in, ratio (as a percent)	7.00%	7.00%
To Be Well Capitalized Minimum Capital Requirements, Ratio (as a percent)	6.50%	6.50%
Tier 1 capital (to risk-weighted assets)
Actual Amount	$ 1,333,686	$ 1,236,289
Actual Ratio (as a percent)	14.03%	13.45%
Minimum Capital Requirement Including Conservation Buffer fully phased-in, ratio (as a percent)	8.50%	8.50%
To Be Well Capitalized Minimum Capital Requirements, Ratio (as a percent)	8.00%	8.00%
Total capital (to risk-weighted assets)
Actual Amount	$ 1,414,838	$ 1,299,453
Actual Ratio (as a percent)	14.88%	14.13%
Minimum Capital Requirement Including Conservation Buffer fully phased-in, ratio (as a percent)	10.50%	10.50%
To Be Well Capitalized Minimum Capital Requirements, Ratio (as a percent)	10.00%	10.00%
Hilltop
Tier 1 capital (to average assets)
Actual Amount	$ 2,045,096	$ 1,822,970
Actual Ratio (as a percent)	12.60%	12.71%
Minimum Capital Requirement Including Conservation Buffer fully phased-in, ratio (as a percent)	4.00%	4.00%
Common equity Tier 1 capital (to risk weighted assets)
Actual Amount	$ 1,980,096	$ 1,776,381
Actual Ratio (as a percent)	18.46%	16.70%
Minimum Capital Requirement Including Conservation Buffer fully phased-in, ratio (as a percent)	7.00%	7.00%
Tier 1 capital (to risk-weighted assets)
Actual Amount	$ 2,045,096	$ 1,822,970
Actual Ratio (as a percent)	19.06%	17.13%
Minimum Capital Requirement Including Conservation Buffer fully phased-in, ratio (as a percent)	8.50%	8.50%
Total capital (to risk-weighted assets)
Actual Amount	$ 2,340,456	$ 1,867,771
Actual Ratio (as a percent)	21.82%	17.55%
Minimum Capital Requirement Including Conservation Buffer fully phased-in, ratio (as a percent)	10.50%	10.50%