Investment Securities (Tables)

12 Months Ended

Dec. 31, 2016

Schedule of investment securities

Investment securities were comprised of the following as of December 31, 2016 and 2015 (amounts in thousands):

	Carrying Value as of  December 31,
	2016		2015
RMBS, available-for-sale	$	253,915	$	176,224
CMBS, fair value option (1)		990,570		1,038,200
Held-to-maturity (“HTM”) securities		509,980		321,244
Equity security, fair value option		12,177		14,498
Subtotal—Investment securities		1,766,642		1,550,166
VIE eliminations (1)		(959,024)		(825,219)
Total investment securities	$	807,618	$	724,947

(1) Certain fair value option CMBS are eliminated in consolidation against VIE liabilities pursuant to ASC 810.

Summary of investments in available-for-sale RMBS and single-borrower CMBS where the fair value option has not been elected

The tables below summarize various attributes of our investments in available‑for‑sale RMBS as of December 31, 2016 and 2015 (amounts in thousands):

							Unrealized Gains or (Losses)
							Recognized in AOCI
	Purchase				Recorded				Gross		Gross		Net
	Amortized		Credit		Amortized		Non-Credit		Unrealized		Unrealized		Fair Value
	Cost		OTTI		Cost		OTTI		Gains		Losses		Adjustment		Fair Value
December 31, 2016
RMBS	$	219,171	$	(10,185)	$	208,986	$	(94)	$	45,113	$	(90)	$	44,929	$	253,915
December 31, 2015
RMBS	$	149,102	$	(10,185)	$	138,917	$	(340)	$	37,647	$	—	$	37,307	$	176,224

	Weighted Average Coupon (1)		Weighted Average Rating	WAL  (Years) (2)
December 31, 2016
RMBS	2.1	%	B	6.1
December 31, 2015
RMBS	1.3	%	B−	6.2

(1) Calculated using the December 31, 2016 and 2015 one-month LIBOR rate of 0.772% and 0.430%, respectively, for floating rate securities.

(2) Represents the WAL of each respective group of securities as of the respective balance sheet date. The WAL of each individual security is calculated using projected amounts and projected timing of future principal payments.

Reconciliation of aggregate principal balance to amortized cost for RMBS and single-borrower CMBS, excluding CMBS where the fair value option is elected

The following table contains a reconciliation of aggregate principal balance to amortized cost for our RMBS as of December 31, 2016 and 2015 (amounts in thousands):

	As of December 31,
	2016		2015
Principal balance	$	399,883	$	233,976
Accretable yield		(64,290)		(68,345)
Non-accretable difference		(126,607)		(26,714)
Total discount		(190,897)		(95,059)
Amortized cost	$	208,986	$	138,917

Schedule of changes to accretable yield and non-accretable difference for RMBS and single-borrower CMBS, excluding CMBS where the fair value option is elected

The following table discloses the changes to accretable yield and non‑accretable difference for our RMBS during the years ended December 31, 2016 and 2015 (amounts in thousands):

			Non-Accretable
	Accretable Yield		Difference
Balance as of January 1, 2015	$	85,495	$	31,752
Accretion of discount		(20,625)		—
Principal write-downs, net		—		(1,563)
Purchases		—		—
Sales		—		—
OTTI		—		—
Transfer to/from non-accretable difference		3,475		(3,475)
Balance as of December 31, 2015		68,345		26,714
Accretion of discount		(15,479)		—
Principal write-downs, net		—		953
Purchases		11,349		99,015
Sales		—		—
OTTI		—		—
Transfer to/from non-accretable difference		75		(75)
Balance as of December 31, 2016	$	64,290	$	126,607

Schedule of gross unrealized losses and estimated fair value of securities in an unrealized loss position, excluding CMBS where the fair value option is elected

The following table presents the gross unrealized losses and estimated fair value of any available‑for‑sale securities that were in an unrealized loss position as of December 31, 2016 and 2015, and for which OTTIs (full or partial) have not been recognized in earnings (amounts in thousands):

	Estimated Fair Value				Unrealized Losses
	Securities with a		Securities with a		Securities with a		Securities with a
	loss less than		loss greater than		loss less than		loss greater than
	12 months		12 months		12 months		12 months
As of December 31, 2016
RMBS	$	8,819	$	957	$	(90)	$	(94)
As of December 31, 2015
RMBS	$	17,026	$	653	$	(180)	$	(160)

Schedule of investment in fair value option CMBS

As of December 31, 2016, none of our CMBS where we have elected the fair value option were variable rate. The table below summarizes various attributes of our investment in fair value option CMBS as of December 31, 2016 and 2015:

	Weighted Average Coupon		Weighted Average Rating (1)	WAL (Years) (2)
December 31, 2016
CMBS, fair value option	5.5	%	C	4.0
December 31, 2015
CMBS, fair value option	3.9	%	CCC+	7.4

(1) As of December 31, 2016 and 2015, excludes $5.1 million and $51.3 million, respectively, in fair value option CMBS that are not rated.

(2) The WAL of each security is calculated based on the period of time over which we expect to receive principal cash flows. Expected principal cash flows are based on contractual payments net of expected losses.

Summary of maturities of preferred equity interests in limited liability companies that own commercial real estate

The table below summarizes the maturities of our HTM CMBS and our HTM preferred equity interests in limited liability companies that own commercial real estate as of December 31, 2016 (amounts in thousands):

			Preferred
	CMBS		Interests		Total
Less than one year	$	209,998	$	—	$	209,998
One to three years		89,927		—		89,927
Three to five years		190,182		—		190,182
Thereafter		—		19,873		19,873
Total	$	490,107	$	19,873	$	509,980

Held-to-maturity

Summary of investments in HTM securities

The table below summarizes unrealized gains and losses of our investments in HTM securities as of December 31, 2016 and 2015 (amounts in thousands):

	Net Carrying Amount		Gross Unrealized		Gross Unrealized
	(Amortized Cost)		Holding Gains		Holding Losses		Fair Value
December 31, 2016
CMBS	$	490,107	$	2,106	$	(8,648)	$	483,565
Preferred interests		19,873		727		—		20,600
Total	$	509,980	$	2,833	$	(8,648)	$	504,165
December 31, 2015
CMBS	$	301,858	$	257	$	(5,651)	$	296,464
Preferred interests		19,386		—		(595)		18,791
Total	$	321,244	$	257	$	(6,246)	$	315,255