Summary of Significant Accounting Policies - Government and Commercial Receivables (Details)	9 Months Ended
Sep. 30, 2018
Accounting Policies [Abstract]
Financing receivable, past due period	90 days

Threshold period past due for delinquent or nonaccrual of financing receivable.

No definition available.

Name:	hasi_ThresholdPeriodPastDueForDelinquentOrNonaccrualOfFinancingReceivable
Namespace Prefix:	hasi_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration