Regulatory Matters - Minimum Capital Requirements (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
PlainsCapital
Tier 1 capital (to average assets)
Actual Amount	$ 1,125,727	$ 1,108,484
Actual Ratio (as a percent)	13.09%	12.35%
Minimum Capital Requirement Including Conservation Buffer in effect at end of period, ratio (as a percent)	4.00%	4.00%
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	$ 1,125,727	$ 1,108,484
Actual Ratio (as a percent)	15.50%	14.64%
Minimum Capital Requirement Including Conservation Buffer in effect at end of period, ratio (as a percent)	5.75%	5.125%
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	$ 1,125,727	$ 1,108,484
Actual Ratio (as a percent)	15.50%	14.64%
Minimum Capital Requirement Including Conservation Buffer in effect at end of period, ratio (as a percent)	7.25%	6.625%
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	$ 1,183,495	$ 1,164,767
Actual Ratio (as a percent)	16.30%	15.38%
Minimum Capital Requirement Including Conservation Buffer in effect at end of period, ratio (as a percent)	9.25%	8.625%
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	$ 1,654,189	$ 1,652,101
Actual Ratio (as a percent)	13.98%	13.51%
Minimum Capital Requirement Including Conservation Buffer in effect at end of period, ratio (as a percent)	4.00%	4.00%
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	$ 1,604,840	$ 1,602,400
Actual Ratio (as a percent)	19.03%	18.30%
Minimum Capital Requirement Including Conservation Buffer in effect at end of period, ratio (as a percent)	5.75%	5.125%
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	$ 1,654,189	$ 1,652,101
Actual Ratio (as a percent)	19.62%	18.87%
Minimum Capital Requirement Including Conservation Buffer in effect at end of period, ratio (as a percent)	7.25%	6.625%
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	$ 1,696,330	$ 1,693,240
Actual Ratio (as a percent)	20.12%	19.34%
Minimum Capital Requirement Including Conservation Buffer in effect at end of period, ratio (as a percent)	9.25%	8.625%
Minimum Capital Requirement Including Conservation Buffer fully phased-in, ratio (as a percent)	10.50%	10.50%