Combined Consolidated Statements of Cash Flows (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Cash flows from operating activities:
Net income	$ 97,626,251	$ 188,733,086	$ 169,454,280
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Loss on extinguishment of debt	149,738	0	0
Depreciation and amortization	28,447,437	21,514,572	3,640,619
Unrealized (gain) loss on derivative instruments	14,378,350	(14,013,966)	(12,694,838)
Unrealized (gain) loss on Agency interest-only securities	(2,143,765)	2,665,188	5,680,893
Provision for loan losses	600,000	600,000	448,833
Amortization of equity based compensation	14,450,764	2,881,447	2,407,773
Amortization of deferred financing costs included in interest expense	5,802,023	4,599,566	3,133,910
Amortization of premium on mortgage loan financing	(629,022)	(533,818)	0
Amortization of above- and below-market lease intangibles	652,068	853,917	0
Accretion/amortization of discount, premium and other fees on loans	(6,917,666)	(3,700,972)	(2,878,027)
Accretion/amortization of discount, premium and other fees on loans	91,306,499	60,320,720	38,212,269
Realized gain on sale of mortgage loan receivables held for sale	(145,274,603)	(146,708,264)	(151,661,150)
Realized gain on real estate securities	(26,977,268)	(4,230,953)	(19,013,960)
Realized gain on sale of real estate, net	(29,760,115)	(13,565,164)	(1,275,235)
Realized gain on assignment of mortgage loan financing	(431,465)	0	0
Origination of mortgage loan receivables held for sale	(3,345,371,937)	(2,013,674,038)	(2,036,138,933)
Repayment of mortgage loan receivables held for sale	1,293,262	5,840,419	75,654,634
Proceeds from sales of mortgage loan receivables held for sale	3,523,688,310	2,345,704,987	1,815,995,772
Accrued interest receivable	(9,686,675)	(2,888,563)	(318,080)
Earnings on investment in unconsolidated joint ventures	(1,990,117)	(3,203,358)	(1,256,109)
Distributions from operations of investment in unconsolidated joint ventures	1,956,695	3,894,303	1,403,687
Deferred tax asset	(7,174,519)	0	0
Changes in operating assets and liabilities:
Due to brokers	0	0	(871,802)
Due from brokers	(2,773)	1,900,210	(1,683,023)
Other assets	(17,446,270)	(17,324,779)	(5,890,951)
Accrued expenses and other liabilities	22,126,726	57,317,794	1,642,506
Net cash provided by (used in) operating activities	208,671,928	476,982,334	(116,006,932)
Cash flows used in investing activities:
Reduction (addition) of cash collateral held by broker for derivatives	(13,864,015)	(10,248,883)	4,640,186
Acquisition of fixed assets	0	0	(351,041)
Purchase of derivative instruments	(7,125)	(20,000)	(226,225)
Purchases of real estate securities	(2,157,391,381)	(1,193,816,283)	(425,796,393)
Repayment of real estate securities	186,310,306	390,628,250	951,150,951
Proceeds from sales of real estate securities	768,592,668	192,387,118	279,275,981
Purchase of FHLB stock	(22,890,000)	(36,350,000)	(13,100,000)
Origination and purchases of mortgage loan receivables held for investment	(1,201,968,254)	(486,072,238)	(341,947,392)
Repayment of mortgage loan receivables held for investment	214,510,727	268,093,305	204,913,202
Reduction (addition) of cash collateral held by broker	(52,825)	45,718,663	(14,351,720)
Addition of deposits received for loan originations	(91,277)	0	0
Security deposits included in other assets	(9,620,677)	(4,356,098)	0
Capital contributions to investment in unconsolidated joint ventures	0	(4,696,405)	(9,265,125)
Distributions of return of capital from investment in unconsolidated joint ventures	3,254,851	7,417,350	6,169,025
Purchases of real estate	(254,497,447)	(289,268,442)	(428,651,275)
Capital improvements of real estate	(5,192,043)	(114,670)	0
Proceeds from sale of real estate	123,443,538	36,929,752	75,646,240
Net cash provided by (used in) investing activities	(2,369,462,954)	(1,083,768,581)	288,106,414
Cash flows from financing activities:
Deferred financing costs	(9,863,387)	(3,190,379)	(10,599,987)
Proceeds from repurchase agreements	10,583,728,059	4,382,307,842	11,348,169,066
Repayment of repurchase agreements	(9,761,897,171)	(4,566,389,752)	(12,151,329,521)
Proceeds from borrowings under credit agreements	69,125,000	30,000,000	0
Repayment of borrowings under credit agreements	(58,125,000)	(30,000,000)	0
Proceeds from borrowings under credit and security agreement	46,750,000	0	0
Proceeds from revolving credit facility	250,000,000	0	0
Repayment of revolving credit facility	(225,000,000)	0	0
Proceeds from mortgage loan financing	188,032,984	185,037,648	88,180,203
Repayment of mortgage loan financing	(30,616,213)	(125,722)	(36,740)
Proceeds from FHLB borrowings	5,448,000,000	4,498,500,000	362,000,000
Repayments of FHLB borrowings	(4,826,000,000)	(3,771,500,000)	(100,000,000)
Proceeds from Notes issued	300,000,000	0	325,000,000
Retirement of Notes issued	(5,594,738)	0	0
Partners’ capital contributions	0	1,800,000	3,000,000
Partners’ capital distributions	(368,983)	(95,442,216)	(76,161,300)
Capital distributed to noncontrolling interests in operating partnership	(47,925,774)	0	0
Capital contributed by noncontrolling interests in consolidated joint ventures	1,840,772	9,845,654	521,875
Capital distributed to noncontrolling interests in consolidated joint ventures	(2,208,125)	(493,136)	(15,625)
Shares acquired to satisfy minimum required federal and state tax withholding on vesting restricted stock	(124,723)	0	0
Issuance of common stock	259,037,500	0	0
Common stock offering costs	(20,523,458)	0	0
Net cash provided by (used in) financing activities	2,158,266,743	640,349,939	(211,272,029)
Net increase (decrease) in cash	(2,524,283)	33,563,692	(39,172,547)
Cash and cash equivalents at beginning of period	78,742,257	45,178,565	84,351,112
Cash and cash equivalents at end of period	76,217,974	78,742,257	45,178,565
Supplemental information:
Cash paid for interest	63,170,972	45,317,028	27,179,564
Cash paid for income taxes	45,980,543	5,392,411	589,042
Supplemental disclosure of non-cash investing activities:
Transfer from mortgage loan receivables held for investment, at amortized cost to mortgage loan receivable held for sale	11,800,000	8,320,273	0
Transfer from real estate and related lease intangibles, net to real estate held for sale	19,321,610	0	0
Supplemental disclosure of non-cash financing activities:
Exchange of capital for common stock	468,694,353	0	0
Exchange of predecessor LP Units for common stock	697,096,682	0	0
Change in deferred tax asset related to change in tax receivable agreement	1,014,034	0	0
Increase in amount payable pursuant to tax receivable agreement	861,929	0	0
Rebalancing of ownership percentage between Company and Operating Partnership	$ 5,329,742	$ 0	$ 0