Fair Value Measurements - Notional Amounts and Fair Values of Derivatives by Product (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Derivatives, Fair Value [Line Items]
Derivatives asset, Notional	$ 398,237	$ 323,108
Derivatives asset, Fair Value	16,375	15,609
Derivative liability, notional	5,152,204	3,268,047
Derivative liability, Fair Value	13,101	14,162
Commodity Contracts [Member] \| Future [Member]
Derivatives, Fair Value [Line Items]
Derivative liability, notional	4,060,000	2,943,000
Derivative liability, Fair Value	709	249
Other Contracts [Member] \| Foreign Exchange Forward [Member]
Derivatives, Fair Value [Line Items]
Derivative liability, notional	400	400
Derivative liability, Fair Value	17	2
Other Contracts [Member] \| Interest Rate Lock Commitments [Member]
Derivatives, Fair Value [Line Items]
Derivatives asset, Notional	248,420	203,648
Derivatives asset, Fair Value	14,024	9,161
Derivative liability, notional		48,638
Derivative liability, Fair Value		923
Other Contracts [Member] \| Forward Start Repurchase Agreement [Member]
Derivatives, Fair Value [Line Items]
Derivative liability, notional	680,000
Derivative liability, Fair Value	0
To Be Announced Security [Member] \| Other Contracts [Member]
Derivatives, Fair Value [Line Items]
Derivatives asset, Notional	135,100	35,650
Derivatives asset, Fair Value	803	4
Derivative liability, notional	132,900	24,350
Derivative liability, Fair Value	798	5
Tba Sale Agreements [Member] \| Other Contracts [Member]
Derivatives, Fair Value [Line Items]
Derivatives asset, Notional	3,480	83,810
Derivatives asset, Fair Value	8	6,444
Derivative liability, notional	257,592	223,846
Derivative liability, Fair Value	11,018	11,614
Auction Rate Securities Purchase Commitment [Member] \| Other Contracts [Member]
Derivatives, Fair Value [Line Items]
Derivatives asset, Notional	11,237
Derivatives asset, Fair Value	1,540
Derivative liability, notional	21,312	27,813
Derivative liability, Fair Value	$ 559	$ 1,369

Nominal or face amount used to calculate payments on the derivative asset.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5579245-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
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+ References

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Nominal or face amount used to calculate payments on the derivative liability.

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