Derivative Financial Instruments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Not designated as hedges | Prime Lending
Derivative financial instruments
Net gain (loss) due to changes in the fair value of the derivative instruments	$ 19,876	$ 18,187
Not designated as hedges | Hilltop Broker-Dealers
Derivative financial instruments
Net gain (loss) due to changes in the fair value of the derivative instruments	(8,141)	(1,807)
Not designated as hedges | PlainsCapital (the Bank)
Derivative financial instruments
Net gain (loss) due to changes in the fair value of the derivative instruments	(135)	$ (61)
IRLCs | Not designated as hedges
Derivative financial instruments
Notional Amount	3,063,446		$ 914,526
Estimated Fair Value	93,412		18,222
Customer-based written options | Not designated as hedges
Derivative financial instruments
Notional Amount	31,200		31,200
Customer-based purchased options | Not designated as hedges
Derivative financial instruments
Notional Amount	31,200		31,200
Commitments to Purchase MBSs | Not designated as hedges
Derivative financial instruments
Notional Amount	5,431,558		3,346,946
Estimated Fair Value	65,666		3,321
Commitments to Sell MBSs | Not designated as hedges
Derivative financial instruments
Notional Amount	9,698,119		5,988,198
Estimated Fair Value	(133,762)		(5,904)
Commitments to Sell MBSs | Not designated as hedges | Prime Lending
Derivative financial instruments
Cash collateral advanced to offset net derivative liability	100,700		4,500
Interest rate swaps | Not designated as hedges
Derivative financial instruments
Notional Amount	41,455		15,012
Estimated Fair Value	(192)		(178)
Interest rate swaps | Cash Flow Hedging | Designated as hedges
Derivative financial instruments
Notional Amount	105,000		50,000
Estimated Fair Value	(3,605)		528
U.S. Treasury bond futures and options | Not designated as hedges
Derivative financial instruments
Notional Amount	66,100		283,500
Eurodollar futures | Not designated as hedges
Derivative financial instruments
Notional Amount	18,000		934,000
Treasury bond futures and options and Eurodollar futures | Not designated as hedges | PrimeLending and Hilltop Broker-Dealers
Derivative financial instruments
Cash collateral advanced to offset net derivative liability	$ 1,000		$ 3,700