Fair Value by Balance Sheet Grouping (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Loans held-for-investment	$ 3,927,095	$ 3,167,913
Loans held-for-investment, at fair value	3,961,948	3,200,980
Available-for-sale securities, at fair value	12,830	12,606
Held-to-maturity securities	19,594	26,696
Held-to-maturity securities, at fair value	19,666	26,611
Cash and cash equivalents	137,355	91,700
Restricted cash	168,809	31,723
Repurchase agreements	1,724,912	1,500,543
Securitized debt obligations	1,124,820	654,263
Securitized debt obligations, at fair value	1,136,007	654,330
Asset-specific financings	114,080	0
Revolving credit facilities	0	75,000
Convertible senior notes	269,241	268,138
Convertible senior notes, at fair value	$ 283,470	$ 270,731

The carrying value as of the balance sheet date of obligations drawn from asset-specific financing facilities.

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The carrying value as of the balance sheet date of obligations drawn from revolving lines of credit.

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Fair value of securitized debt obligations.

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Amount to be repaid to the counterparty to the repurchase agreement when the carrying amount (or market value, if higher than the carrying amount) of securities or other assets sold under the repurchase agreement exceeds 10 percent of total assets.

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Obligation reflecting another party's right to economic interests in another entity or trust under a contractual right. For example, an investor may purchase a beneficial interest in a securitization transaction.

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Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

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Fair value portion of borrowing which can be exchanged for a specified number of another security at the option of the issuer or the holder, for example, but not limited to, the entity's common stock.

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Including the current and noncurrent portions, carrying value as of the balance sheet date of a written promise to pay a note, initially due after one year or beyond the operating cycle if longer, which can be exchanged for a specified amount of one or more securities (typically common stock), at the option of the issuer or the holder.

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Amount of investment in debt security measured at amortized cost (held-to-maturity).

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Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements and loans held for sale.

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Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

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Fair value of securitized, pay-through debt securities collateralized by real estate mortgage loans classified as held-to-maturity.

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Amount of cash and cash equivalents restricted as to withdrawal or usage. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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