Loans - Ratings (Details) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2016 USD ($) loan	Dec. 31, 2015 USD ($)
Investments in loans
Total gross loans	$ 6,435,659	$ 6,269,546
Total gross loans (as a percent)	100.00%	100.00%
Amount of loan impairment charges on individual loans held-for-investment	$ 0	$ 0
Investment and Servicing Segment
Investments in loans
Carrying amount of loans in default	8,200
Rating 1
Investments in loans
Total gross loans	$ 6,533	664
Total gross loans (as a percent)	0.10%
Rating 1 \| Maximum
Investments in loans
LTV (as a percent)	65.00%
Rating 2
Investments in loans
Total gross loans	$ 661,929	$ 675,678
Total gross loans (as a percent)	10.30%	10.80%
Rating 2 \| Maximum
Investments in loans
LTV (as a percent)	70.00%
Rating 3
Investments in loans
Total gross loans	$ 5,253,590	$ 4,987,459
Total gross loans (as a percent)	81.60%	79.60%
Rating 3 \| Maximum
Investments in loans
LTV (as a percent)	80.00%
Rating 4
Investments in loans
Total gross loans	$ 351,220	$ 401,880
Total gross loans (as a percent)	5.50%	6.40%
Allowance for loan losses as a percent of carrying amount	1.50%
Rating 4 \| Minimum
Investments in loans
LTV (as a percent)	80.00%
Rating 4 \| Maximum
Investments in loans
LTV (as a percent)	90.00%
Rating 5
Investments in loans
Allowance for loan losses as a percent of carrying amount	5.00%
Rating 5 \| Minimum
Investments in loans
LTV (as a percent)	90.00%
N/A
Investments in loans
Total gross loans	$ 162,387	$ 203,865
Total gross loans (as a percent)	2.50%	3.20%
Total loans held-for-investment
Investments in loans
Total gross loans	$ 6,192,922	$ 5,979,108
Total loans held-for-investment \| First Mortgages, excluding Cost Recovery Loans
Investments in loans
Total gross loans	5,022,325	4,723,852
Total loans held-for-investment \| First Mortgages, excluding Cost Recovery Loans \| Rating 1
Investments in loans
Total gross loans	6,533	664
Total loans held-for-investment \| First Mortgages, excluding Cost Recovery Loans \| Rating 2
Investments in loans
Total gross loans	477,910	496,372
Total loans held-for-investment \| First Mortgages, excluding Cost Recovery Loans \| Rating 3
Investments in loans
Total gross loans	4,331,630	3,979,247
Total loans held-for-investment \| First Mortgages, excluding Cost Recovery Loans \| Rating 4
Investments in loans
Total gross loans	206,252	247,569
Total loans held-for-investment \| Subordinated mortgages
Investments in loans
Total gross loans	392,315	392,563
Total loans held-for-investment \| Subordinated mortgages \| Rating 2
Investments in loans
Total gross loans	85,363	88,857
Total loans held-for-investment \| Subordinated mortgages \| Rating 3
Investments in loans
Total gross loans	286,702	270,435
Total loans held-for-investment \| Subordinated mortgages \| Rating 4
Investments in loans
Total gross loans	20,250	33,271
Total loans held-for-investment \| Mezzanine Loans
Investments in loans
Total gross loans	770,120	862,693
Total loans held-for-investment \| Mezzanine Loans \| Rating 2
Investments in loans
Total gross loans	98,656	90,449
Total loans held-for-investment \| Mezzanine Loans \| Rating 3
Investments in loans
Total gross loans	546,746	651,204
Total loans held-for-investment \| Mezzanine Loans \| Rating 4
Investments in loans
Total gross loans	124,718	121,040
Total loans held-for-investment \| Cost Recovery Loans
Investments in loans
Total gross loans	8,162
Total loans held-for-investment \| Cost Recovery Loans \| N/A
Investments in loans
Total gross loans	8,162
Loans held-for-sale
Investments in loans
Total gross loans	$ 154,225	203,865
Number of held-for-sale loans with the fair value option elected that were 90 days past due or greater or on nonaccrual status \| loan	0
Loans held-for-sale \| N/A
Investments in loans
Total gross loans	$ 154,225	203,865
Loans transferred as secured borrowings
Investments in loans
Total gross loans	88,512	86,573
Loans transferred as secured borrowings \| Rating 3
Investments in loans
Total gross loans	$ 88,512	$ 86,573

Represents the amount of impairment charges on individual mortgage loans of real estate that are held for investment.

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- Definition

Represents the range of loan to value ratio that is used to classify a loan into a particular credit rating category.

+ References

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- Definition

Represents the allowance for loan losses as a percent of carrying amount.

+ References

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- Definition

Represents the carrying amount of the outstanding balance due under the mortgage loan that are under default.

+ References

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- Definition

The gross carrying amount of the outstanding balance due under the mortgage loan.

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- Definition

The gross carrying amount of the outstanding balance due under the mortgage loan as a percentage of total loans.

+ References

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- Definition

Represents the number of held-for-sale loans with the fair value option elected that were 90 days past due or greater or on nonaccrual status.

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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.

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