Mortgage Banking Activities, Net - Components of Mortgage Banking Activities (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Mortgage Loans on Real Estate [Line Items]
Mortgage banking activities, net	$ 9,766	$ 1,333	$ 24,712	$ 10,706
Residential Mortgage Banking Activities
Mortgage Loans on Real Estate [Line Items]
Other income (expense), net / other fee income	382	1,177	606	3,209
Mortgage banking activities, net	9,766	331	26,774	7,383
Residential Mortgage Banking Activities \| Residential loans, at fair value
Mortgage Loans on Real Estate [Line Items]
Changes in fair value of assets	12,671	36,183	47,456	54,375
Residential Mortgage Banking Activities \| Sequoia securities
Mortgage Loans on Real Estate [Line Items]
Changes in fair value of assets	0	0	1,455	(14,359)
Residential Mortgage Banking Activities \| Risk management derivatives, net
Mortgage Loans on Real Estate [Line Items]
Risk management derivatives	(3,287)	(37,029)	(22,743)	(35,842)
Commercial Mortgage Banking Activities
Mortgage Loans on Real Estate [Line Items]
Other income (expense), net / other fee income	0	109	43	336
Mortgage banking activities, net	0	1,002	(2,062)	3,323
Commercial Mortgage Banking Activities \| Risk management derivatives, net
Mortgage Loans on Real Estate [Line Items]
Risk management derivatives	0	(3,081)	(2,538)	(7,832)
Commercial Mortgage Banking Activities \| Commercial loans, at fair value
Mortgage Loans on Real Estate [Line Items]
Changes in fair value of assets	$ 0	$ 3,974	$ 433	$ 10,819

Increase (Decrease) in Fair Value Adjustments on Assets

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- Definition

The net income attributable to mortgage banking activities. This includes market valuations related to residential and commercial loans, Sequoia IOs, and mortgage banking derivatives, as well as realized gains or losses associated with mortgage loan sales.

+ References

No definition available.

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- Definition

Amount of unrealized gain (loss) related to the fair value of price risk derivatives designated as fair value hedging instruments, as offset by the gain (loss) on the hedged item to the extent that the fair value hedge is determined to be effective.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5624171-113959

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Fees and other service revenues recognized in the period that are not otherwise specified in the taxonomy.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1(d))
-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

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