Commitments and Contingencies - Unfunded and Other Commitments (Details) $ in Millions	Jun. 30, 2023 USD ($)
Unfunded commitments
Leasehold improvement allowance, unfunded, pending milestone achievement	$ 250.6
Future funding obligation, amount	271.2
Performance-based commitments	$ 127.7

Represents the off-balance sheet unfunded maximum amount of funds for construction and development loans and build-outs of space in net lease assets over a period of time if and when the borrowers and tenants meet established milestones and other performance criteria.

No definition available.

Name:	safe_PerformanceBasedCommitments
Namespace Prefix:	safe_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant