Summary of Significant Accounting Policies - Investments in Unconsolidated Entities (Details) - USD ($) $ in Thousands		12 Months Ended
	Dec. 18, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2014
Business Acquisition [Line Items]
Percentage of interest held		97.10%	97.50%
Acquisition price		$ 1,414,179	$ 1,285,185
Investment in unconsolidated entity		$ (2,871)	$ 903
Jeff Orleans Medical Development Real Estate L L C
Business Acquisition [Line Items]
Percentage of interest held				40.00%
Acquisition price				$ 1,300
Desert Cove MOB, LLC [Member]
Business Acquisition [Line Items]
Percentage of interest held			43.00%
Noncontrolling interest, increase from business combination, percent		57.00%
Acquisition price	$ 4,560	$ 4,600
Investment in unconsolidated entity		$ 5,500