Related Party Arrangements - Narrative - Investment Management Fee (Details)	12 Months Ended
Dec. 31, 2018
Advisor [Member] \| Advisor [Member] \| Investment Management Fees [Member]
Related Party Transaction [Line Items]
Monthly investment management fee, percentage	0.06667%

Represents the monthly investment management fee percentage charged on the total cost of investments in properties and real estate related assets below specified threshold (as defined by agreement).

No definition available.

Name:	sfr_InvestmentManagementMonthlyFeePercentageOfRealPropertiesOrRelatedAssetsAcquired
Namespace Prefix:	sfr_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration