Significant Accounting Policies - Investment in Real Estate (Details)	12 Months Ended
	Dec. 31, 2019
Land improvements | Minimum
Real estate
Estimated useful life (in years)	15 years
Land improvements | Maximum
Real estate
Estimated useful life (in years)	20 years
Buildings | Minimum
Real estate
Estimated useful life (in years)	20 years
Buildings | Maximum
Real estate
Estimated useful life (in years)	40 years
Building improvements | Minimum
Real estate
Estimated useful life (in years)	5 years
Building improvements | Maximum
Real estate
Estimated useful life (in years)	25 years