Derivative Financial Instruments (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Not Designated as Hedging Instrument | PrimeLending
Derivative financial instruments
Net gain (loss) due to changes in the fair value of the derivative instruments	$ 700	$ 12,500
Not Designated as Hedging Instrument | PlainsCapital
Derivative financial instruments
Net gain (loss) due to changes in the fair value of the derivative instruments	100	(500)
Not Designated as Hedging Instrument | Hilltop Broker-Dealers
Derivative financial instruments
Net gain (loss) due to changes in the fair value of the derivative instruments	6,300	$ 6,900
Interest Rate Lock Commitments
Derivative financial instruments
Notional Amount	1,427,763		$ 944,550
Estimated Fair Value	40,911		23,269
Customer-based written options
Derivative financial instruments
Notional Amount	2,223
Estimated Fair Value	97
Customer-based purchased options
Derivative financial instruments
Notional Amount	2,223
Estimated Fair Value	(97)
Commitments to Purchase MBSs
Derivative financial instruments
Notional Amount	3,567,436		3,616,922
Estimated Fair Value	14,090		(1,155)
Commitments to Sell MBSs
Derivative financial instruments
Notional Amount	5,881,086		5,609,250
Estimated Fair Value	(18,960)		(532)
Commitments to Sell MBSs | PrimeLending
Derivative financial instruments
Cash collateral advanced to offset net derivative liability	6,100		19,100
Interest Rate Swap and Swaptions
Derivative financial instruments
Notional Amount	32,239		32,452
Estimated Fair Value	(159)		(283)
U.S. Treasury bond futures and options
Derivative financial instruments
Notional Amount	206,000		297,000
U.S. Treasury bond futures and options | PrimeLending
Derivative financial instruments
Cash collateral advanced to offset net derivative liability	$ 3,200		$ 3,200