Fair Value Measurements - Notional Amounts and Fair Values of Derivatives by Product (Details) - Not Designated as Hedging Instrument - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Derivatives, Fair Value [Line Items]
Derivatives asset, Notional	$ 160,075	$ 297,727
Derivatives asset, Fair Value	1,427	1,663
Derivative liability, notional	5,138,702	4,756,631
Derivative liability, Fair Value	1,874	2,024
Other Contracts | TBA
Derivatives, Fair Value [Line Items]
Derivatives asset, Notional	62,550	169,500
Derivatives asset, Fair Value	333	332
Derivative liability, notional	55,650	169,500
Derivative liability, Fair Value	249	289
Other Contracts | TBA Purchase Contracts [Member]
Derivatives, Fair Value [Line Items]
Derivative liability, notional		121,573
Derivative liability, Fair Value		923
Other Contracts | TBA Sale Agreements
Derivatives, Fair Value [Line Items]
Derivatives asset, Notional	90,871	121,573
Derivatives asset, Fair Value	216	482
Other Contracts | ARS Purchase Commitments [Member]
Derivatives, Fair Value [Line Items]
Derivatives asset, Notional		6,654
Derivatives asset, Fair Value		849
Other Contracts | Foreign currency forward contracts
Derivatives, Fair Value [Line Items]
Derivative liability, notional	400	200
Derivative liability, Fair Value	4	1
Other Contracts | Auction Rate Securities Purchase Commitment
Derivatives, Fair Value [Line Items]
Derivatives asset, Notional	6,654
Derivatives asset, Fair Value	878
Derivative liability, notional	19,781	24,358
Derivative liability, Fair Value	359	645
Other Contracts | TBA Purchase Agreements [Member] [Member]
Derivatives, Fair Value [Line Items]
Derivative liability, notional	90,871
Derivative liability, Fair Value	536
Other Contracts | Forward Start Repurchase Agreement [Member]
Derivatives, Fair Value [Line Items]
Derivative liability, notional	627,000	382,000
Derivative liability, Fair Value	0	0
Commodity Contracts | Futures
Derivatives, Fair Value [Line Items]
Derivative liability, notional	4,345,000	4,059,000	[1]
Derivative liability, Fair Value	$ 726	$ 166	[1]

[1] For the three months ended March 31, 2017, the diluted earnings per share computation does not include the anti-dilutive effect of 1,334,607 shares of Class A Stock granted under share-based compensation arrangements (1,295,972 shares for the three months ended March 31, 2016 ).(2)Represents net income (loss) from discontinued operations less net income (loss) attributable to noncontrolling interest, net of tax divided by weighted average number of shares outstanding.