Fair Value Measurements (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014	Oct. 02, 2014
Fair Value Measurements
Aggregate fair value of PrimeLending's mortgage loans held for sale accounted for under the Fair Value Option	$ 1,190,000,000	$ 1,270,000,000
Unpaid principal balance of PrimeLending loans held for sale accounted under the fair value option	1,140,000,000	1,220,000,000
Financial assets and liabilities
Trading securities	320,153,000us-gaap_TradingSecurities	65,717,000us-gaap_TradingSecurities
Available for sale securities	859,212,000us-gaap_AvailableForSaleSecurities	925,535,000us-gaap_AvailableForSaleSecurities
Level 2
Financial assets and liabilities
Loans held for sale	27,056,000	37,541,000
Estimate of Fair Value Measurement
Financial assets and liabilities
Loans held for sale	27,056,000	37,541,000
Recurring \| Level 1
Financial assets and liabilities
Trading securities	40,000	39,000
Available for sale securities	14,070,000	13,762,000
Investment in SWS common stock		70,282,000
Recurring \| Level 2
Financial assets and liabilities
Trading securities	314,181,000	65,678,000
Available for sale securities	845,142,000	911,773,000
Loans held for sale	1,168,757,000	1,263,135,000
Derivative assets	49,649,000	23,805,000
Trading liabilities	139,481,000	48,000
Derivative liabilities	22,048,000	12,849,000
Recurring \| Level 3
Financial assets and liabilities
Trading securities	5,932,000
Loans held for sale	19,495,000	9,017,000
Mortgage servicing asset	31,648,000	36,155,000
Recurring \| Estimate of Fair Value Measurement
Financial assets and liabilities
Trading securities	320,153,000	65,717,000
Available for sale securities	859,212,000	925,535,000
Loans held for sale	1,188,252,000	1,272,152,000
Derivative assets	49,649,000	23,805,000
Mortgage servicing asset	31,648,000	36,155,000
Investment in SWS common stock		70,282,000
Trading liabilities	139,481,000	48,000
Derivative liabilities	22,048,000	12,849,000
SWS
Fair value measurements
Number of shares of common stock available to purchase under warrant			8,695,652
Warrants exercise price (in dollars per share)			$ 5.75
Aggregate principal amount of senior unsecured loan			$ 50,000,000
Percentage of outstanding shares of SWS common stock			21.00%

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Represents the aggregate fair value of loans held for sale accounted for under the fair value option.

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

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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Exercise price per share or per unit of warrants or rights outstanding.

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Number of securities into which the class of warrant or right may be converted. For example, but not limited to, 500,000 warrants may be converted into 1,000,000 shares.

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Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

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Fair value portion of investments in an entity not consolidated. Includes, but is not limited to, investments in an entity that is affiliated with the reporting entity by means of direct or indirect ownership, an entity in which the reporting entity shares control of the entity with another party or group, an entity which the company has significant influence, but does not have control and subsidiaries that are not required to be consolidated and are accounted for using the equity or cost method.

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Fair value portion of loans held-for-sale including, but not limited to, mortgage loans and finance receivables.

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Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

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Fair value of an asset representing net future revenue from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs related to servicing arrangements.

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Fair value portion of liabilities pertaining to principal and customer trading transactions, or which may be incurred with the objective of generating a profit from short-term fluctuations in price as part of an entity's market-making, hedging and proprietary trading. Examples include, but are not limited to, short positions in securities, derivatives and commodities.

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Amount of investments in debt and equity securities and other forms of securities that provide ownership interests classified as trading.

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