Consolidated Statement Of Operations Consolidated Statement of Operations (Parenthetical) - USD ($) $ in Thousands		3 Months Ended																12 Months Ended
		Dec. 31, 2018		Sep. 30, 2018		Jun. 30, 2018		Mar. 31, 2018		Dec. 31, 2017		Sep. 30, 2017		Jun. 30, 2017	[3]	Mar. 31, 2017	[3]	Dec. 31, 2018		Dec. 31, 2017
Securitization Transactions [Line Items]
Management fee rebate	[1]	$ 400		$ 400		$ 300		$ 300		$ 200		$ 200						$ 1,380		$ 332
Interest income		35,694	[2]	35,300	[2]	31,941	[2]	28,092	[2]	23,810	[3]	21,145	[3]	$ 21,788		$ 22,886		131,027	[4]	89,629	[4]
Interest expense		16,083	[2]	15,678	[2]	13,383	[2]	11,562	[2]	9,326	[3]	$ 8,166	[3]	$ 7,625		$ 6,003		56,707	[4]	31,120	[4]
Consolidated Entities [Member]
Securitization Transactions [Line Items]
Interest income		2,100		1,300		1,300		1,300		1,500								6,000		1,500
Interest expense		$ 1,200		$ 700		$ 800		$ 900		$ 600								$ 3,600		$ 600

[1] See Note 9 for further details on management fee rebates.

[2] Includes interest income and interest expense of a consolidated securitization trust of $1.3 million and $0.9 million, respectively, for the three-month period ended March 31, 2018. Includes interest income and interest expense of a consolidated securitization trust of $1.3 million and $0.8 million, respectively, for the three-month period ended June 30, 2018. Includes interest income and interest expense of a consolidated securitization trust of $1.3 million and $0.7 million, respectively, for the three-month period ended September 30, 2018. Includes interest income and interest expense of a consolidated securitization trust of $2.1 million and $1.2 million, respectively, for the three-month period ended December 31, 2018. See Note 6 for further details on the Company's consolidated securitization trusts.

[3] Includes interest income and interest expense of a consolidated securitization trust of $1.5 million and $0.6 million, respectively, for the thee-month period ended December 31, 2017. See Note 6 for further details on the Company's consolidated securitization trusts.

[4] Includes interest income and interest expense of consolidated securitization trusts of $6.0 million and $3.6 million, respectively, for the year ended December 31, 2018. Includes interest income and interest expense of a consolidated securitization trust of $1.5 million and $0.6 million, respectively, for the year ended December 31, 2017. See Note 6 for further details on the Company's consolidated securitization trust.