Fair Value Measurements - Notional Amounts and Fair Values of Derivatives by Product (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Derivatives, Fair Value [Line Items]
Derivatives asset, Notional	$ 623,523us-gaap_DerivativeAssetNotionalAmount	$ 440,884us-gaap_DerivativeAssetNotionalAmount
Derivatives asset, Fair Value	16,782	12,111
Derivative liability, notional	3,212,139	5,011,304
Derivative liability, Fair Value	2,025	3,505
Other Contracts [Member] \| Interest Rate Lock Commitments [Member]
Derivatives, Fair Value [Line Items]
Derivatives asset, Notional	238,734	147,521
Derivatives asset, Fair Value	11,424	7,576
Derivative liability, notional	13,345	22,269
Derivative liability, Fair Value	544	1,222
Other Contracts [Member] \| Foreign Exchange Forward [Member]
Derivatives, Fair Value [Line Items]
Derivative liability, notional	1,000	400,000
Other Contracts [Member] \| To Be Announced Security [Member]
Derivatives, Fair Value [Line Items]
Derivatives asset, Notional	44,295	105,185
Derivatives asset, Fair Value	230	1,026
Derivative liability, notional	38,345	105,186
Derivative liability, Fair Value	199	1,018
Other Contracts [Member] \| Forward Start Repurchase Agreement [Member]
Derivatives, Fair Value [Line Items]
Derivative liability, notional		636,000
Derivative liability, Fair Value		0
Other Contracts [Member] \| Tba Sale Agreements [Member]
Derivatives, Fair Value [Line Items]
Derivatives asset, Notional	340,494	188,178
Derivatives asset, Fair Value	5,128	3,509
Other Contracts [Member] \| Foreign Exchange Forward [Member]
Derivatives, Fair Value [Line Items]
Derivative liability, Fair Value	3	10
Other Contracts [Member] \| Auction Rate Securities Purchase Commitment [Member]
Derivatives, Fair Value [Line Items]
Derivative liability, notional	14,249	12,249
Derivative liability, Fair Value	797	902
Commodity Contracts [Member] \| Future [Member]
Derivatives, Fair Value [Line Items]
Derivative liability, notional	3,145,200	3,835,600
Derivative liability, Fair Value	$ 482	$ 353

Fair value, after offset of derivative liability, of 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, before offset against an obligation to return collateral under a master netting arrangement. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

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Fair value, after offset of derivative asset, of financial liability or 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, elected not to be and before offset against a right to receive collateral under a master netting arrangement. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

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