Properties (Details) $ in Thousands, ft² in Millions	1 Months Ended		3 Months Ended		12 Months Ended			24 Months Ended
	Dec. 31, 2017 item	Sep. 30, 2017 ft² property	Mar. 31, 2020 USD ($) property item	Mar. 31, 2019 item	Dec. 31, 2018 item	Dec. 31, 2016 ft² item	Dec. 31, 2015 item	Dec. 31, 2018 item	Dec. 31, 2019 USD ($)
Properties
Number of properties sold | item			0	0
Summary of properties
Properties, cost			$ 2,497,686						$ 2,490,630
Less: accumulated depreciation			(244,616)						(224,190)
Properties, net			2,253,070						2,266,440
Property Segment
Summary of properties
Land and land improvements			484,673						484,397
Buildings and building improvements			1,688,284						1,687,756
Furniture & fixtures			$ 54,277						52,567
Property Segment | Minimum
Summary of properties
Land improvements, useful life			0 years
Building and building improvements, useful life			5 years
Furniture & fixtures, useful life			3 years
Property Segment | Maximum
Summary of properties
Land improvements, useful life			15 years
Building and building improvements, useful life			45 years
Furniture & fixtures, useful life			7 years
Investing and Servicing Segment
Summary of properties
Land and land improvements			$ 54,150						54,052
Buildings and building improvements			186,329						182,048
Furniture & fixtures			$ 2,265						2,139
Investing and Servicing Segment | Minimum
Summary of properties
Land improvements, useful life			0 years
Building and building improvements, useful life			3 years
Furniture & fixtures, useful life			2 years
Investing and Servicing Segment | Maximum
Summary of properties
Land improvements, useful life			15 years
Building and building improvements, useful life			40 years
Furniture & fixtures, useful life			5 years
Commercial and Residential Lending Segment
Summary of properties
Land and land improvements			$ 11,386						11,386
Buildings			$ 16,322						$ 16,285
Commercial and Residential Lending Segment | Minimum
Summary of properties
Land improvements, useful life			0 years
Building, useful life			10 years
Commercial and Residential Lending Segment | Maximum
Summary of properties
Land improvements, useful life			7 years
Building, useful life			23 years
Woodstar Portfolio
Properties
Number of properties in portfolio investment | item			32
Total gross properties and lease intangibles			$ 631,100
Debt			$ 477,800
Number of units acquired | item			8,948
Number of acquired properties closed | item						14	18
Woodstar II Portfolio
Properties
Number of properties in portfolio investment | item			27
Total gross properties and lease intangibles			$ 606,400
Debt			$ 436,900
Number of units in portfolio investment | item			6,109
Number of acquired properties closed | item	8				19			27
Medical Office Portfolio
Properties
Area of property | ft²						1.9
Total gross properties and lease intangibles			$ 759,900
Debt			590,800
Number of acquired properties closed | item						34
Master Lease Portfolio
Properties
Total gross properties and lease intangibles			343,800
Debt			192,500
Number of retail properties acquired | property		16
Number of square feet of properties | ft²		1.9
Term of master lease agreements		24 years 7 months 6 days
REIS Equity Portfolio
Properties
Total gross properties and lease intangibles			282,200
Debt			$ 197,900
Number of retail properties acquired | property			16
Number of equity interests in unconsolidated commercial real estate properties | property			1
Utah, Florida, Texas and Minnesota | Master Lease Portfolio | Minimum
Properties
Concentration risk (as a percent)		50.00%