Real Estate Leases - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($)	Dec. 31, 2015 Customers	Dec. 31, 2014 Customers
Concentration Risk [Line Items]
Approximate Investment in real estate properties subject to outstanding contractual option to purchase | $	$ 173.7
Customer Concentration Risk [Member] | Sales Revenue, Net [Member]
Concentration Risk [Line Items]
Concentration risk (percent)	9.80%	9.80%	10.50%
Customer Concentration Risk [Member] | Sales Revenue, Net [Member] | Baylor Health System [Member]
Concentration Risk [Line Items]
Number of customer account for 10% or more of company's revenues including revenue from discontinued operations | Customers		1	1
Concentration risk (percent)		10.00%	10.00%