Related Party Arrangements - Schedule of Amounts Attributable to the Advisor and its Affiliates - Amounts Incurred, Paid, and Payable (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Steadfast Income Advisor, LLC [Member] | General and Administrative Expense [Member]
Related Party Transaction [Line Items]
Incurred in the period	$ 4,717,463
Steadfast Income Advisor, LLC [Member] | Advisor and its Affiliates [Member]
Related Party Transaction [Line Items]
Incurred in the period	39,249,788	$ 51,092,503	$ 47,808,767
Paid in the period	36,264,112	51,949,697	47,753,106
Payable (Prepaid) at the end of the period	4,791,863	1,806,187
Steadfast Income Advisor, LLC [Member] | Advisor and its Affiliates [Member] | Investment Management Fees [Member]
Related Party Transaction [Line Items]
Payable (Prepaid) at the end of the period	1,640,485	0
Steadfast Income Advisor, LLC [Member] | Advisor and its Affiliates [Member] | Acquisition Fees [Member]
Related Party Transaction [Line Items]
Incurred in the period	705,722	0	0
Paid in the period	705,722	0	0
Steadfast Income Advisor, LLC [Member] | Advisor and its Affiliates [Member] | Acquisition Expenses [Member]
Related Party Transaction [Line Items]
Payable (Prepaid) at the end of the period	211,188	0
Steadfast Income Advisor, LLC [Member] | Advisor and its Affiliates [Member] | Property Management, Fees [Member]
Related Party Transaction [Line Items]
Payable (Prepaid) at the end of the period	334,577	402,315
Steadfast Income Advisor, LLC [Member] | Advisor and its Affiliates [Member] | Property Management, Reimbursement of Onsite Personnel [Member]
Related Party Transaction [Line Items]
Payable (Prepaid) at the end of the period	589,551	772,584
Steadfast Income Advisor, LLC [Member] | Advisor and its Affiliates [Member] | Property Management, Other Fees [Member]
Related Party Transaction [Line Items]
Payable (Prepaid) at the end of the period	39,349	44,981
Steadfast Income Advisor, LLC [Member] | Advisor and its Affiliates [Member] | Other Operating Expenses [Member]
Related Party Transaction [Line Items]
Payable (Prepaid) at the end of the period	115,212	87,221
Steadfast Income Advisor, LLC [Member] | Advisor and its Affiliates [Member] | Disposition Fees [Member]
Related Party Transaction [Line Items]
Payable (Prepaid) at the end of the period	2,052,750	566,625
Steadfast Income Advisor, LLC [Member] | Advisor and its Affiliates [Member] | Refinancing Fee [Member]
Related Party Transaction [Line Items]
Payable (Prepaid) at the end of the period	0	86,675
Steadfast Income Advisor, LLC [Member] | Advisor and its Affiliates [Member] | Prepaid Insurance Deductible Account [Member]
Related Party Transaction [Line Items]
Incurred in the period	1,597,712	1,285,490	311,794
Paid in the period	1,555,825	1,322,247	361,490
Payable (Prepaid) at the end of the period	(119,055)	(160,942)
Steadfast Income Advisor, LLC [Member] | Advisor and its Affiliates [Member] | Insurance Proceeds [Member]
Related Party Transaction [Line Items]
Payable (Prepaid) at the end of the period	(75,000)	0
Steadfast Income Advisor, LLC [Member] | Advisor and its Affiliates [Member] | Construction Management Fees [Member]
Related Party Transaction [Line Items]
Incurred in the period	209,829	526,866	1,493,999
Paid in the period	213,652	536,866	1,548,701
Payable (Prepaid) at the end of the period	2,608	6,431
Steadfast Income Advisor, LLC [Member] | Advisor and its Affiliates [Member] | Construction Management Reimbursement of Labor Costs [Member]
Related Party Transaction [Line Items]
Incurred in the period	95,631	239,015	367,204
Paid in the period	95,730	245,889	474,155
Payable (Prepaid) at the end of the period	198	297
Steadfast Income Advisor, LLC [Member] | Advisor and its Affiliates [Member] | Capital Expenditures [Member]
Related Party Transaction [Line Items]
Incurred in the period	39,680	74,709	17,654
Paid in the period	39,680	74,709	17,654
Steadfast Income Advisor, LLC [Member] | Advisor and its Affiliates [Member] | Deferred Financing Costs [Member]
Related Party Transaction [Line Items]
Incurred in the period	0	12,930	139,229
Paid in the period	0	12,930	139,229
Steadfast Income Advisor, LLC [Member] | Advisor and its Affiliates [Member] | Capitalized Costs on Investment in Unconsolidated Joint Venture [Member]
Related Party Transaction [Line Items]
Incurred in the period	58,386	65,113	0
Paid in the period	58,386	65,113	0
Steadfast Income Advisor, LLC [Member] | Advisor and its Affiliates [Member] | Capitalized Acquisition Expenses [Member]
Related Party Transaction [Line Items]
Incurred in the period	245,048	3,226	0
Paid in the period	245,048	3,226	0
Steadfast Income Advisor, LLC [Member] | Advisor and its Affiliates [Member] | Fees to Affiliates [Member] | Investment Management Fees [Member]
Related Party Transaction [Line Items]
Incurred in the period	9,799,335	13,823,000	14,075,818
Paid in the period	8,158,850	15,008,001	14,060,587
Steadfast Income Advisor, LLC [Member] | Advisor and its Affiliates [Member] | Fees to Affiliates [Member] | Acquisition Fees [Member]
Related Party Transaction [Line Items]
Incurred in the period	0	0	960
Paid in the period	0	0	960
Steadfast Income Advisor, LLC [Member] | Advisor and its Affiliates [Member] | Fees to Affiliates [Member] | Property Management, Fees [Member]
Related Party Transaction [Line Items]
Incurred in the period	4,059,216	6,278,850	6,406,479
Paid in the period	4,126,954	6,410,591	6,392,550
Steadfast Income Advisor, LLC [Member] | Advisor and its Affiliates [Member] | Fees to Affiliates [Member] | Property Management, Other Fees [Member]
Related Party Transaction [Line Items]
Incurred in the period	1,598,991	1,771,620	1,673,724
Paid in the period	1,604,623	1,781,318	1,671,282
Steadfast Income Advisor, LLC [Member] | Advisor and its Affiliates [Member] | Fees to Affiliates [Member] | Property Management, Other Fees, Property Operations [Member]
Related Party Transaction [Line Items]
Incurred in the period	138,235	170,067	0
Paid in the period	138,235	170,067	0
Steadfast Income Advisor, LLC [Member] | Advisor and its Affiliates [Member] | Fees to Affiliates [Member] | Property Management, Other Fees, General and Administrative [Member]
Related Party Transaction [Line Items]
Incurred in the period	86,542	133,419	168,037
Paid in the period	86,542	133,419	168,037
Steadfast Income Advisor, LLC [Member] | Advisor and its Affiliates [Member] | Fees to Affiliates [Member] | Disposition Transaction Costs [Member]
Related Party Transaction [Line Items]
Incurred in the period	84,222	56,922	0
Steadfast Income Advisor, LLC [Member] | Advisor and its Affiliates [Member] | Acquisition Costs [Member] | Acquisition Expenses [Member]
Related Party Transaction [Line Items]
Incurred in the period	444,475	0	0
Paid in the period	233,287	0	0
Steadfast Income Advisor, LLC [Member] | Advisor and its Affiliates [Member] | Operating, Maintenance and Management [Member] | Property Management, Reimbursement of Onsite Personnel [Member]
Related Party Transaction [Line Items]
Incurred in the period	12,857,437	18,716,284	18,751,492
Paid in the period	13,040,470	18,748,974	18,650,009
Steadfast Income Advisor, LLC [Member] | Advisor and its Affiliates [Member] | General and Administrative Expense [Member] | Other Operating Expenses [Member]
Related Party Transaction [Line Items]
Incurred in the period	988,367	1,244,264	1,232,493
Paid in the period	960,376	1,341,997	1,098,568
Steadfast Income Advisor, LLC [Member] | Advisor and its Affiliates [Member] | General and Administrative Expense [Member] | Refinancing Fee [Member]
Related Party Transaction [Line Items]
Incurred in the period	422,160	86,675	3,283,737
Paid in the period	508,835	0	3,283,737
Steadfast Income Advisor, LLC [Member] | Advisor and its Affiliates [Member] | General and Administrative Expense [Member] | Insurance Proceeds [Member]
Related Party Transaction [Line Items]
Incurred in the period	75,000	102,147	113,853
Paid in the period	0	(102,147)	(113,853)
Steadfast Income Advisor, LLC [Member] | Advisor and its Affiliates [Member] | Sales of Real Estate [Member] | Disposition Fees [Member]
Related Party Transaction [Line Items]
Incurred in the period	5,893,800	6,706,200	0
Paid in the period	4,407,675	6,139,575	0
Steadfast Income Advisor, LLC [Member] | Advisor and its Affiliates [Member] | Sales of Real Estate [Member] | Disposition Transaction Costs [Member]
Related Party Transaction [Line Items]
Paid in the period	$ 84,222	$ 56,922	$ 0