Securitization Transactions Narrative (Details) - USD ($) $ in Thousands |
6 Months Ended | ||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Jun. 30, 2018 |
Dec. 31, 2017 |
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| Securitization Transactions [Line Items] | |||||||||||||||||||||||
| Face amount of notes distributed from Risk Retention Vehicle | $ 5,600 | ||||||||||||||||||||||
| Investments Fair Value | $ 2,625,471 | $ 2,071,707 | |||||||||||||||||||||
| Minimum economic interest required to be retained | 5.00% | ||||||||||||||||||||||
| Participation in Multi-Seller Consumer Loan Securitization [Member] | |||||||||||||||||||||||
| Securitization Transactions [Line Items] | |||||||||||||||||||||||
| Aggregate unpaid principal balance of loans sold | $ 124,000 | ||||||||||||||||||||||
| Company's share of loans sold | 51.00% | ||||||||||||||||||||||
| Co-participants share of loans sold | 49.00% | ||||||||||||||||||||||
| Gain (Loss) on Securitization of Financial Assets | $ (100) | ||||||||||||||||||||||
| Senior notes issued in securitization transaction | 87,000 | ||||||||||||||||||||||
| Subordinated notes issued in securitization transaction | $ 18,700 | ||||||||||||||||||||||
| Company's initial percentage ownership of jointly owned entity | 51.00% | ||||||||||||||||||||||
| Affiliated co-participants initial percentage ownership of jointly owned entity | 49.00% | ||||||||||||||||||||||
| Company's current percentage ownership of jointly owned entity | 75.00% | 75.00% | |||||||||||||||||||||
| CLO I Securitization [Member] | |||||||||||||||||||||||
| Securitization Transactions [Line Items] | |||||||||||||||||||||||
| Gain (Loss) on Securitization of Financial Assets | $ 200 | ||||||||||||||||||||||
| Percentage non-controlling ownership of related party | 25.00% | ||||||||||||||||||||||
| The Company [Member] | CLO I Securitization [Member] | |||||||||||||||||||||||
| Securitization Transactions [Line Items] | |||||||||||||||||||||||
| Corporate loans transferred into CLO securitization | $ 62,000 | ||||||||||||||||||||||
| Affiliated Entity [Member] | CLO I Securitization [Member] | |||||||||||||||||||||||
| Securitization Transactions [Line Items] | |||||||||||||||||||||||
| Corporate loans transferred into CLO securitization | 141,700 | ||||||||||||||||||||||
| Collateralized Loan Obligations [Member] | |||||||||||||||||||||||
| Securitization Transactions [Line Items] | |||||||||||||||||||||||
| Investments Fair Value | 210,321 | [1],[2] | $ 210,816 | [3],[4] | |||||||||||||||||||
| Collateralized Loan Obligations [Member] | CLO I Securitization [Member] | |||||||||||||||||||||||
| Securitization Transactions [Line Items] | |||||||||||||||||||||||
| Investments Fair Value | [5],[6] | 18,215 | [7] | 24,299 | [8] | ||||||||||||||||||
| Collateralized Loan Obligations [Member] | CLO II Securitization [Member] | |||||||||||||||||||||||
| Securitization Transactions [Line Items] | |||||||||||||||||||||||
| Investments Fair Value | [6],[8] | 16,806 | 13,395 | ||||||||||||||||||||
| Collateralized Loan Obligations [Member] | Distributed from Risk Retention Vehicle [Member] | |||||||||||||||||||||||
| Securitization Transactions [Line Items] | |||||||||||||||||||||||
| Investments Fair Value | 5,000 | ||||||||||||||||||||||
| Corporate Equity Investments [Member] | |||||||||||||||||||||||
| Securitization Transactions [Line Items] | |||||||||||||||||||||||
| Investments Fair Value | 45,505 | [1],[2] | 37,465 | [3],[4] | |||||||||||||||||||
| Corporate Equity Investments [Member] | CLO I Securitization [Member] | |||||||||||||||||||||||
| Securitization Transactions [Line Items] | |||||||||||||||||||||||
| Investments Fair Value | [3],[4],[9] | 5,300 | $ 5,000 | ||||||||||||||||||||
| Non-QM loan securitization [Member] | |||||||||||||||||||||||
| Securitization Transactions [Line Items] | |||||||||||||||||||||||
| Notes issued by non-QM securitization trust | $ 141,200 | ||||||||||||||||||||||
| Economic interest retained | 5.10% | ||||||||||||||||||||||
| Cost of notes purchased from securitization trust | $ 700 | ||||||||||||||||||||||
| Threshold for exercising Optional Redemption | 30.00% | ||||||||||||||||||||||
| Percentage used to calculate servicing administrator fee | 0.03% | ||||||||||||||||||||||
| Non-QM loan securitization [Member] | The Company [Member] | |||||||||||||||||||||||
| Securitization Transactions [Line Items] | |||||||||||||||||||||||
| Non-QM loans transferred into securitization trust | $ 141,200 | ||||||||||||||||||||||
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