Fair Value Measurements - Summary of Investments Classified as Level 3 (Detail) - USD ($)	3 Months Ended			12 Months Ended
	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Investment owned at fair value, beginning balance		$ 101,028,104		$ 101,028,104	$ 53,447,442
Purchases of investments				252,220,803	138,369,032
Maturities or payments of investments				(150,208,509)	(90,475,779)
Accretion of discounts				496,068	5,833
Net change in unrealized appreciation (depreciation) on investments	$ 318,424	(59,077)	$ (318,424)	259,347	(318,424)
Investment owned at Fair value, ending balance	203,795,813		101,028,104	203,795,813	101,028,104
Senior Secured Term Loans [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Investment owned at fair value, beginning balance		5,474,534		5,474,534
Purchases of investments				24,200,000	5,500,000
Maturities or payments of investments				(1,381,848)	(25,466)
Accretion of discounts				380,801
Investment owned at Fair value, ending balance	28,673,487		5,474,534	28,673,487	5,474,534
Senior Secured Term Loan Participations [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Investment owned at fair value, beginning balance		18,484,242		18,484,242	5,750,000
Purchases of investments				42,170,621	13,446,833
Maturities or payments of investments				(2,637,793)	(400,000)
Accretion of discounts				115,267	5,833
Net change in unrealized appreciation (depreciation) on investments				318,424	(318,424)
Investment owned at Fair value, ending balance	58,450,761		18,484,242	58,450,761	18,484,242
Senior Secured Trade Finance Participations [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Investment owned at fair value, beginning balance		$ 77,069,328		77,069,328	47,697,442
Purchases of investments				165,850,182	119,422,199
Maturities or payments of investments				(126,188,868)	(90,050,313)
Net change in unrealized appreciation (depreciation) on investments				(59,077)
Investment owned at Fair value, ending balance	$ 116,671,565		$ 77,069,328	116,671,565	$ 77,069,328
Unsecured Short Term Note Receivable [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Purchases of investments				20,000,000
Maturities or payments of investments				$ (20,000,000)