Fair Value Measurements - FV Option (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Fair Value Measurements
Mortgage loans held for sale, fair value	$ 2,090	$ 1,940
Mortgage loans held for sale, unpaid principal balance	$ 2,000	$ 1,880

Represents the amount of unpaid principal balance of loans held for sale accounted under the fair value option.

No definition available.

Name:	hth_FairValueOptionLoansHeldForSaleUnpaidPrincipalBalance
Namespace Prefix:	hth_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant